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_.isEqual(value, other)
_.isEqual对两个值执行深度比较来确定是否它们是相等的
注意：此方法支持比较arrays, array buffers, booleans, date objects, error objects, maps, numbers, `Object` objects, regexes, sets, strings, symbols, typed arrays。Object对象会比较它们自身非继承可枚举的属性。不支持function和DOM节点的比较
参数
value (*): 需要比较的值
other (*): 需要比较的另外一个值
返回值
(boolean): 如果两个值相等返回true，否则false
例子
var object = { 'a': 1 }; var other = { 'a': 1 }; _.isEqual(object, other); // => true object === other; // => false
源代码
/** * lodash (Custom Build) <https://lodash.com/> * Build: `lodash modularize exports="npm" -o ./` * Copyright jQuery Foundation and other contributors <https://jquery.org/> * Released under MIT license <https://lodash.com/license> * Based on Underscore.js 1.8.3 <http://underscorejs.org/LICENSE> * Copyright Jeremy Ashkenas, DocumentCloud and Investigative Reporters & Editors */ /** Used as the size to enable large array optimizations. */ var LARGE_ARRAY_SIZE = 200; /** Used to stand-in for `undefined` hash values. */ var HASH_UNDEFINED = '__lodash_hash_undefined__'; /** Used to compose bitmasks for comparison styles. */ var UNORDERED_COMPARE_FLAG = 1, PARTIAL_COMPARE_FLAG = 2; /** Used as references for various `Number` constants. */ var MAX_SAFE_INTEGER = 9007199254740991; /** `Object#toString` result references. */ var argsTag = '[object Arguments]', arrayTag = '[object Array]', boolTag = '[object Boolean]', dateTag = '[object Date]', errorTag = '[object Error]', funcTag = '[object Function]', genTag = '[object GeneratorFunction]', mapTag = '[object Map]', numberTag = '[object Number]', objectTag = '[object Object]', promiseTag = '[object Promise]', regexpTag = '[object RegExp]', setTag = '[object Set]', stringTag = '[object String]', symbolTag = '[object Symbol]', weakMapTag = '[object WeakMap]'; var arrayBufferTag = '[object ArrayBuffer]', dataViewTag = '[object DataView]', float32Tag = '[object Float32Array]', float64Tag = '[object Float64Array]', int8Tag = '[object Int8Array]', int16Tag = '[object Int16Array]', int32Tag = '[object Int32Array]', uint8Tag = '[object Uint8Array]', uint8ClampedTag = '[object Uint8ClampedArray]', uint16Tag = '[object Uint16Array]', uint32Tag = '[object Uint32Array]'; /** * Used to match `RegExp` * [syntax characters](http://ecma-international.org/ecma-262/7.0/#sec-patterns). */ var reRegExpChar = /[\\^$.*+?()[\]{}|]/g; /** Used to detect host constructors (Safari). */ var reIsHostCtor = /^\[object .+?Constructor\]$/; /** Used to detect unsigned integer values. */ var reIsUint = /^(?:0|[1-9]\d*)$/; /** Used to identify `toStringTag` values of typed arrays. */ var typedArrayTags = {}; typedArrayTags[float32Tag] = typedArrayTags[float64Tag] = typedArrayTags[int8Tag] = typedArrayTags[int16Tag] = typedArrayTags[int32Tag] = typedArrayTags[uint8Tag] = typedArrayTags[uint8ClampedTag] = typedArrayTags[uint16Tag] = typedArrayTags[uint32Tag] = true; typedArrayTags[argsTag] = typedArrayTags[arrayTag] = typedArrayTags[arrayBufferTag] = typedArrayTags[boolTag] = typedArrayTags[dataViewTag] = typedArrayTags[dateTag] = typedArrayTags[errorTag] = typedArrayTags[funcTag] = typedArrayTags[mapTag] = typedArrayTags[numberTag] = typedArrayTags[objectTag] = typedArrayTags[regexpTag] = typedArrayTags[setTag] = typedArrayTags[stringTag] = typedArrayTags[weakMapTag] = false; /** Detect free variable `global` from Node.js. */ var freeGlobal = typeof global == 'object' && global && global.Object === Object && global; /** Detect free variable `self`. */ var freeSelf = typeof self == 'object' && self && self.Object === Object && self; /** Used as a reference to the global object. */ var root = freeGlobal || freeSelf || Function('return this')(); /** Detect free variable `exports`. */ var freeExports = typeof exports == 'object' && exports && !exports.nodeType && exports; /** Detect free variable `module`. */ var freeModule = freeExports && typeof module == 'object' && module && !module.nodeType && module; /** Detect the popular CommonJS extension `module.exports`. */ var moduleExports = freeModule && freeModule.exports === freeExports; /** Detect free variable `process` from Node.js. */ var freeProcess = moduleExports && freeGlobal.process; /** Used to access faster Node.js helpers. */ var nodeUtil = (function() { try { return freeProcess && freeProcess.binding('util'); } catch (e) {} }()); /* Node.js helper references. */ var nodeIsTypedArray = nodeUtil && nodeUtil.isTypedArray; /** * A specialized version of `_.some` for arrays without support for iteratee * shorthands. * * @private * @param {Array} [array] The array to iterate over. * @param {Function} predicate The function invoked per iteration. * @returns {boolean} Returns `true` if any element passes the predicate check, * else `false`. */ function arraySome(array, predicate) { var index = -1, length = array ? array.length : 0; while (++index < length) { if (predicate(array[index], index, array)) { return true; } } return false; } /** * The base implementation of `_.times` without support for iteratee shorthands * or max array length checks. * * @private * @param {number} n The number of times to invoke `iteratee`. * @param {Function} iteratee The function invoked per iteration. * @returns {Array} Returns the array of results. */ function baseTimes(n, iteratee) { var index = -1, result = Array(n); while (++index < n) { result[index] = iteratee(index); } return result; } /** * The base implementation of `_.unary` without support for storing metadata. * * @private * @param {Function} func The function to cap arguments for. * @returns {Function} Returns the new capped function. */ function baseUnary(func) { return function(value) { return func(value); }; } /** * Gets the value at `key` of `object`. * * @private * @param {Object} [object] The object to query. * @param {string} key The key of the property to get. * @returns {*} Returns the property value. */ function getValue(object, key) { return object == null ? undefined : object[key]; } /** * Checks if `value` is a host object in IE < 9. * * @private * @param {*} value The value to check. * @returns {boolean} Returns `true` if `value` is a host object, else `false`. */ function isHostObject(value) { // Many host objects are `Object` objects that can coerce to strings // despite having improperly defined `toString` methods. var result = false; if (value != null && typeof value.toString != 'function') { try { result = !!(value + ''); } catch (e) {} } return result; } /** * Converts `map` to its key-value pairs. * * @private * @param {Object} map The map to convert. * @returns {Array} Returns the key-value pairs. */ function mapToArray(map) { var index = -1, result = Array(map.size); map.forEach(function(value, key) { result[++index] = [key, value]; }); return result; } /** * Creates a unary function that invokes `func` with its argument transformed. * * @private * @param {Function} func The function to wrap. * @param {Function} transform The argument transform. * @returns {Function} Returns the new function. */ function overArg(func, transform) { return function(arg) { return func(transform(arg)); }; } /** * Converts `set` to an array of its values. * * @private * @param {Object} set The set to convert. * @returns {Array} Returns the values. */ function setToArray(set) { var index = -1, result = Array(set.size); set.forEach(function(value) { result[++index] = value; }); return result; } /** Used for built-in method references. */ var arrayProto = Array.prototype, funcProto = Function.prototype, objectProto = Object.prototype; /** Used to detect overreaching core-js shims. */ var coreJsData = root['__core-js_shared__']; /** Used to detect methods masquerading as native. */ var maskSrcKey = (function() { var uid = /[^.]+$/.exec(coreJsData && coreJsData.keys && coreJsData.keys.IE_PROTO || ''); return uid ? ('Symbol(src)_1.' + uid) : ''; }()); /** Used to resolve the decompiled source of functions. */ var funcToString = funcProto.toString; /** Used to check objects for own properties. */ var hasOwnProperty = objectProto.hasOwnProperty; /** * Used to resolve the * [`toStringTag`](http://ecma-international.org/ecma-262/7.0/#sec-object.prototype.tostring) * of values. */ var objectToString = objectProto.toString; /** Used to detect if a method is native. */ var reIsNative = RegExp('^' + funcToString.call(hasOwnProperty).replace(reRegExpChar, '\\$&') .replace(/hasOwnProperty|(function).*?(?=\\\()| for .+?(?=\\\])/g, '$1.*?') + '$' ); /** Built-in value references. */ var Symbol = root.Symbol, Uint8Array = root.Uint8Array, propertyIsEnumerable = objectProto.propertyIsEnumerable, splice = arrayProto.splice; /* Built-in method references for those with the same name as other `lodash` methods. */ var nativeKeys = overArg(Object.keys, Object); /* Built-in method references that are verified to be native. */ var DataView = getNative(root, 'DataView'), Map = getNative(root, 'Map'), Promise = getNative(root, 'Promise'), Set = getNative(root, 'Set'), WeakMap = getNative(root, 'WeakMap'), nativeCreate = getNative(Object, 'create'); /** Used to detect maps, sets, and weakmaps. */ var dataViewCtorString = toSource(DataView), mapCtorString = toSource(Map), promiseCtorString = toSource(Promise), setCtorString = toSource(Set), weakMapCtorString = toSource(WeakMap); /** Used to convert symbols to primitives and strings. */ var symbolProto = Symbol ? Symbol.prototype : undefined, symbolValueOf = symbolProto ? symbolProto.valueOf : undefined; /** * Creates a hash object. * * @private * @constructor * @param {Array} [entries] The key-value pairs to cache. */ function Hash(entries) { var index = -1, length = entries ? entries.length : 0; this.clear(); while (++index < length) { var entry = entries[index]; this.set(entry[0], entry[1]); } } /** * Removes all key-value entries from the hash. * * @private * @name clear * @memberOf Hash */ function hashClear() { this.__data__ = nativeCreate ? nativeCreate(null) : {}; } /** * Removes `key` and its value from the hash. * * @private * @name delete * @memberOf Hash * @param {Object} hash The hash to modify. * @param {string} key The key of the value to remove. * @returns {boolean} Returns `true` if the entry was removed, else `false`. */ function hashDelete(key) { return this.has(key) && delete this.__data__[key]; } /** * Gets the hash value for `key`. * * @private * @name get * @memberOf Hash * @param {string} key The key of the value to get. * @returns {*} Returns the entry value. */ function hashGet(key) { var data = this.__data__; if (nativeCreate) { var result = data[key]; return result === HASH_UNDEFINED ? undefined : result; } return hasOwnProperty.call(data, key) ? data[key] : undefined; } /** * Checks if a hash value for `key` exists. * * @private * @name has * @memberOf Hash * @param {string} key The key of the entry to check. * @returns {boolean} Returns `true` if an entry for `key` exists, else `false`. */ function hashHas(key) { var data = this.__data__; return nativeCreate ? data[key] !== undefined : hasOwnProperty.call(data, key); } /** * Sets the hash `key` to `value`. * * @private * @name set * @memberOf Hash * @param {string} key The key of the value to set. * @param {*} value The value to set. * @returns {Object} Returns the hash instance. */ function hashSet(key, value) { var data = this.__data__; data[key] = (nativeCreate && value === undefined) ? HASH_UNDEFINED : value; return this; } // Add methods to `Hash`. Hash.prototype.clear = hashClear; Hash.prototype['delete'] = hashDelete; Hash.prototype.get = hashGet; Hash.prototype.has = hashHas; Hash.prototype.set = hashSet; /** * Creates an list cache object. * * @private * @constructor * @param {Array} [entries] The key-value pairs to cache. */ function ListCache(entries) { var index = -1, length = entries ? entries.length : 0; this.clear(); while (++index < length) { var entry = entries[index]; this.set(entry[0], entry[1]); } } /** * Removes all key-value entries from the list cache. * * @private * @name clear * @memberOf ListCache */ function listCacheClear() { this.__data__ = []; } /** * Removes `key` and its value from the list cache. * * @private * @name delete * @memberOf ListCache * @param {string} key The key of the value to remove. * @returns {boolean} Returns `true` if the entry was removed, else `false`. */ function listCacheDelete(key) { var data = this.__data__, index = assocIndexOf(data, key); if (index < 0) { return false; } var lastIndex = data.length - 1; if (index == lastIndex) { data.pop(); } else { splice.call(data, index, 1); } return true; } /** * Gets the list cache value for `key`. * * @private * @name get * @memberOf ListCache * @param {string} key The key of the value to get. * @returns {*} Returns the entry value. */ function listCacheGet(key) { var data = this.__data__, index = assocIndexOf(data, key); return index < 0 ? undefined : data[index][1]; } /** * Checks if a list cache value for `key` exists. * * @private * @name has * @memberOf ListCache * @param {string} key The key of the entry to check. * @returns {boolean} Returns `true` if an entry for `key` exists, else `false`. */ function listCacheHas(key) { return assocIndexOf(this.__data__, key) > -1; } /** * Sets the list cache `key` to `value`. * * @private * @name set * @memberOf ListCache * @param {string} key The key of the value to set. * @param {*} value The value to set. * @returns {Object} Returns the list cache instance. */ function listCacheSet(key, value) { var data = this.__data__, index = assocIndexOf(data, key); if (index < 0) { data.push([key, value]); } else { data[index][1] = value; } return this; } // Add methods to `ListCache`. ListCache.prototype.clear = listCacheClear; ListCache.prototype['delete'] = listCacheDelete; ListCache.prototype.get = listCacheGet; ListCache.prototype.has = listCacheHas; ListCache.prototype.set = listCacheSet; /** * Creates a map cache object to store key-value pairs. * * @private * @constructor * @param {Array} [entries] The key-value pairs to cache. */ function MapCache(entries) { var index = -1, length = entries ? entries.length : 0; this.clear(); while (++index < length) { var entry = entries[index]; this.set(entry[0], entry[1]); } } /** * Removes all key-value entries from the map. * * @private * @name clear * @memberOf MapCache */ function mapCacheClear() { this.__data__ = { 'hash': new Hash, 'map': new (Map || ListCache), 'string': new Hash }; } /** * Removes `key` and its value from the map. * * @private * @name delete * @memberOf MapCache * @param {string} key The key of the value to remove. * @returns {boolean} Returns `true` if the entry was removed, else `false`. */ function mapCacheDelete(key) { return getMapData(this, key)['delete'](key); } /** * Gets the map value for `key`. * * @private * @name get * @memberOf MapCache * @param {string} key The key of the value to get. * @returns {*} Returns the entry value. */ function mapCacheGet(key) { return getMapData(this, key).get(key); } /** * Checks if a map value for `key` exists. * * @private * @name has * @memberOf MapCache * @param {string} key The key of the entry to check. * @returns {boolean} Returns `true` if an entry for `key` exists, else `false`. */ function mapCacheHas(key) { return getMapData(this, key).has(key); } /** * Sets the map `key` to `value`. * * @private * @name set * @memberOf MapCache * @param {string} key The key of the value to set. * @param {*} value The value to set. * @returns {Object} Returns the map cache instance. */ function mapCacheSet(key, value) { getMapData(this, key).set(key, value); return this; } // Add methods to `MapCache`. MapCache.prototype.clear = mapCacheClear; MapCache.prototype['delete'] = mapCacheDelete; MapCache.prototype.get = mapCacheGet; MapCache.prototype.has = mapCacheHas; MapCache.prototype.set = mapCacheSet; /** * * Creates an array cache object to store unique values. * * @private * @constructor * @param {Array} [values] The values to cache. */ function SetCache(values) { var index = -1, length = values ? values.length : 0; this.__data__ = new MapCache; while (++index < length) { this.add(values[index]); } } /** * Adds `value` to the array cache. * * @private * @name add * @memberOf SetCache * @alias push * @param {*} value The value to cache. * @returns {Object} Returns the cache instance. */ function setCacheAdd(value) { this.__data__.set(value, HASH_UNDEFINED); return this; } /** * Checks if `value` is in the array cache. * * @private * @name has * @memberOf SetCache * @param {*} value The value to search for. * @returns {number} Returns `true` if `value` is found, else `false`. */ function setCacheHas(value) { return this.__data__.has(value); } // Add methods to `SetCache`. SetCache.prototype.add = SetCache.prototype.push = setCacheAdd; SetCache.prototype.has = setCacheHas; /** * Creates a stack cache object to store key-value pairs. * * @private * @constructor * @param {Array} [entries] The key-value pairs to cache. */ function Stack(entries) { this.__data__ = new ListCache(entries); } /** * Removes all key-value entries from the stack. * * @private * @name clear * @memberOf Stack */ function stackClear() { this.__data__ = new ListCache; } /** * Removes `key` and its value from the stack. * * @private * @name delete * @memberOf Stack * @param {string} key The key of the value to remove. * @returns {boolean} Returns `true` if the entry was removed, else `false`. */ function stackDelete(key) { return this.__data__['delete'](key); } /** * Gets the stack value for `key`. * * @private * @name get * @memberOf Stack * @param {string} key The key of the value to get. * @returns {*} Returns the entry value. */ function stackGet(key) { return this.__data__.get(key); } /** * Checks if a stack value for `key` exists. * * @private * @name has * @memberOf Stack * @param {string} key The key of the entry to check. * @returns {boolean} Returns `true` if an entry for `key` exists, else `false`. */ function stackHas(key) { return this.__data__.has(key); } /** * Sets the stack `key` to `value`. * * @private * @name set * @memberOf Stack * @param {string} key The key of the value to set. * @param {*} value The value to set. * @returns {Object} Returns the stack cache instance. */ function stackSet(key, value) { var cache = this.__data__; if (cache instanceof ListCache) { var pairs = cache.__data__; if (!Map || (pairs.length < LARGE_ARRAY_SIZE - 1)) { pairs.push([key, value]); return this; } cache = this.__data__ = new MapCache(pairs); } cache.set(key, value); return this; } // Add methods to `Stack`. Stack.prototype.clear = stackClear; Stack.prototype['delete'] = stackDelete; Stack.prototype.get = stackGet; Stack.prototype.has = stackHas; Stack.prototype.set = stackSet; /** * Creates an array of the enumerable property names of the array-like `value`. * * @private * @param {*} value The value to query. * @param {boolean} inherited Specify returning inherited property names. * @returns {Array} Returns the array of property names. */ function arrayLikeKeys(value, inherited) { // Safari 8.1 makes `arguments.callee` enumerable in strict mode. // Safari 9 makes `arguments.length` enumerable in strict mode. var result = (isArray(value) || isArguments(value)) ? baseTimes(value.length, String) : []; var length = result.length, skipIndexes = !!length; for (var key in value) { if ((inherited || hasOwnProperty.call(value, key)) && !(skipIndexes && (key == 'length' || isIndex(key, length)))) { result.push(key); } } return result; } /** * Gets the index at which the `key` is found in `array` of key-value pairs. * * @private * @param {Array} array The array to inspect. * @param {*} key The key to search for. * @returns {number} Returns the index of the matched value, else `-1`. */ function assocIndexOf(array, key) { var length = array.length; while (length--) { if (eq(array[length][0], key)) { return length; } } return -1; } /** * The base implementation of `getTag`. * * @private * @param {*} value The value to query. * @returns {string} Returns the `toStringTag`. */ function baseGetTag(value) { return objectToString.call(value); } /** * The base implementation of `_.isEqual` which supports partial comparisons * and tracks traversed objects. * * @private * @param {*} value The value to compare. * @param {*} other The other value to compare. * @param {Function} [customizer] The function to customize comparisons. * @param {boolean} [bitmask] The bitmask of comparison flags. * The bitmask may be composed of the following flags: * 1 - Unordered comparison * 2 - Partial comparison * @param {Object} [stack] Tracks traversed `value` and `other` objects. * @returns {boolean} Returns `true` if the values are equivalent, else `false`. */ //_.isEqual的基础实现，深度比较两个对象是否是相等的 //value要比较的对象，other要比较的另一个对象，customizer自定义比较方法 //bitmask为1说明是无序的比较，为2说明是部分比较 //stack追踪传入的参数，防止发生循环引用 function baseIsEqual(value, other, customizer, bitmask, stack) { if (value === other) {//如果value和other严格相等，直接返回true return true; } if (value == null || other == null || (!isObject(value) && !isObjectLike(other))) { //判断有值为空或者NaN，反正不是数组或对象的情况 return value !== value && other !== other; } return baseIsEqualDeep(value, other, baseIsEqual, customizer, bitmask, stack); //调用baseIsEqualDeep来判断 } /** * A specialized version of `baseIsEqual` for arrays and objects which performs * deep comparisons and tracks traversed objects enabling objects with circular * references to be compared. * * @private * @param {Object} object The object to compare. * @param {Object} other The other object to compare. * @param {Function} equalFunc The function to determine equivalents of values. * @param {Function} [customizer] The function to customize comparisons. * @param {number} [bitmask] The bitmask of comparison flags. See `baseIsEqual` * for more details. * @param {Object} [stack] Tracks traversed `object` and `other` objects. * @returns {boolean} Returns `true` if the objects are equivalent, else `false`. */ //深度比较数组和对象是否相等 function baseIsEqualDeep(object, other, equalFunc, customizer, bitmask, stack) { var objIsArr = isArray(object),//判断object是不是数组 othIsArr = isArray(other),//判断other是不是数组 objTag = arrayTag,//'[object Array]' othTag = arrayTag;//'[object Array]' if (!objIsArr) { objTag = getTag(object);//如果object不是数组，就获取object的数据类型tag objTag = objTag == argsTag ? objectTag : objTag; } if (!othIsArr) { othTag = getTag(other);//如果other不是数组，就获取other的数据类型tag othTag = othTag == argsTag ? objectTag : othTag; } var objIsObj = objTag == objectTag && !isHostObject(object),//object是对象类型且不是宿主对象 othIsObj = othTag == objectTag && !isHostObject(other),//other是对象类型且不是宿主对象 isSameTag = objTag == othTag;//object和other的类型tag一样 if (isSameTag && !objIsObj) {//object和other的tag相等且它们不是本地对象类型 stack || (stack = new Stack);//新建一个ListCache类型数据，ListCache其实就是一个自己实现的Map数据类型 return (objIsArr || isTypedArray(object)) ? equalArrays(object, other, equalFunc, customizer, bitmask, stack) : equalByTag(object, other, objTag, equalFunc, customizer, bitmask, stack); //如果都是数组类型或者typedArray类型就调用equalArrays方法判断 //否则调用equalByTag判断 } if (!(bitmask & PARTIAL_COMPARE_FLAG)) {//如果不是部分比较，且是object类型 var objIsWrapped = objIsObj && hasOwnProperty.call(object, '__wrapped__'), othIsWrapped = othIsObj && hasOwnProperty.call(other, '__wrapped__'); //判断object和other上有没有__wrapped__属性，就是判断它们是不是lodash包裹对象 //单文件的lodash代码中有LodashWrapper方法会创建`lodash` wrapper objects if (objIsWrapped || othIsWrapped) {//如果object和other其中有一个是lodash包裹对象 var objUnwrapped = objIsWrapped ? object.value() : object, othUnwrapped = othIsWrapped ? other.value() : other; //获取lodash包裹对象的值，然后再传递给baseIsEqual处理 stack || (stack = new Stack); return equalFunc(objUnwrapped, othUnwrapped, customizer, bitmask, stack); } } if (!isSameTag) {//如果toStringTag不一样，直接返回false return false; } stack || (stack = new Stack); return equalObjects(object, other, equalFunc, customizer, bitmask, stack); //其他情况使用equalObjects来判断 } /** * The base implementation of `_.isNative` without bad shim checks. * * @private * @param {*} value The value to check. * @returns {boolean} Returns `true` if `value` is a native function, * else `false`. */ function baseIsNative(value) { if (!isObject(value) || isMasked(value)) { return false; } var pattern = (isFunction(value) || isHostObject(value)) ? reIsNative : reIsHostCtor; return pattern.test(toSource(value)); } /** * The base implementation of `_.isTypedArray` without Node.js optimizations. * * @private * @param {*} value The value to check. * @returns {boolean} Returns `true` if `value` is a typed array, else `false`. */ function baseIsTypedArray(value) { return isObjectLike(value) && isLength(value.length) && !!typedArrayTags[objectToString.call(value)]; } /** * The base implementation of `_.keys` which doesn't treat sparse arrays as dense. * * @private * @param {Object} object The object to query. * @returns {Array} Returns the array of property names. */ function baseKeys(object) { if (!isPrototype(object)) { return nativeKeys(object); } var result = []; for (var key in Object(object)) { if (hasOwnProperty.call(object, key) && key != 'constructor') { result.push(key); } } return result; } /** * A specialized version of `baseIsEqualDeep` for arrays with support for * partial deep comparisons. * * @private * @param {Array} array The array to compare. * @param {Array} other The other array to compare. * @param {Function} equalFunc The function to determine equivalents of values. * @param {Function} customizer The function to customize comparisons. * @param {number} bitmask The bitmask of comparison flags. See `baseIsEqual` * for more details. * @param {Object} stack Tracks traversed `array` and `other` objects. * @returns {boolean} Returns `true` if the arrays are equivalent, else `false`. */ //深度比较数组是否相等 //partical部分比较的意思就是，other的长度可以比array长，other在包含array所有元素的情况下，还可以有自己的独特于array的元素 function equalArrays(array, other, equalFunc, customizer, bitmask, stack) { var isPartial = bitmask & PARTIAL_COMPARE_FLAG,//判断是否是部分比较，判断对应的掩码二进制位 arrLength = array.length,//array长度 othLength = other.length;//other长度 if (arrLength != othLength && !(isPartial && othLength > arrLength)) {//长度不符合要求，直接返回false return false; } // Assume cyclic values are equal. //假设循环值都是相等的 //stack默认是listCache对象，是自己实现的Map数据类型 var stacked = stack.get(array); if (stacked && stack.get(other)) {//从stack中获取array和other，以防出现循环引用的情况 return stacked == other; } var index = -1,//循环索引 result = true,//一开始先假设循环值都是相等的 seen = (bitmask & UNORDERED_COMPARE_FLAG) ? new SetCache : undefined; //如果是无序比较，就实例化一个SetCache对象 stack.set(array, other);//stack上存下array和other stack.set(other, array); // Ignore non-index properties. while (++index < arrLength) {//循环array的长度 var arrValue = array[index],//当前循环的array值 othValue = other[index];//当前循环的other值 if (customizer) {//如果提供了customizer比较方法，就用它来比较，partial部分比较要反过来传递array和other var compared = isPartial ? customizer(othValue, arrValue, index, other, array, stack) : customizer(arrValue, othValue, index, array, other, stack); } if (compared !== undefined) {//如果自定义比较有了结果，且为真，就continue继续下一次循环，否则result=false，跳出循环 if (compared) { continue; } result = false; break; } // Recursively compare arrays (susceptible to call stack limits). //递归地比较数组元素值是否相等（容易溢出调用栈） if (seen) {//如果创建了seen变量，说明是无序比较 //seen是SetCache对象，也是利用key-value形式存储值 //遍历other，如果有值和当前array的值相等，相等的otherValue的index就存入seen中，并且arraySome返回true，否则返回false跳出循环 if (!arraySome(other, function(othValue, othIndex) { if (!seen.has(othIndex) && (arrValue === othValue || equalFunc(arrValue, othValue, customizer, bitmask, stack))) { return seen.add(othIndex); } })) { result = false; break; } } else if (!( arrValue === othValue || equalFunc(arrValue, othValue, customizer, bitmask, stack) )) {//如果不是无序比较，就先用严格等于比较，如果严格等于不合适，就递归调用baseIsEqual继续判断获取结果 result = false; break; } } stack['delete'](array);//清除stack stack['delete'](other); return result; } /** * A specialized version of `baseIsEqualDeep` for comparing objects of * the same `toStringTag`. * * **Note:** This function only supports comparing values with tags of * `Boolean`, `Date`, `Error`, `Number`, `RegExp`, or `String`. * * @private * @param {Object} object The object to compare. * @param {Object} other The other object to compare. * @param {string} tag The `toStringTag` of the objects to compare. * @param {Function} equalFunc The function to determine equivalents of values. * @param {Function} customizer The function to customize comparisons. * @param {number} bitmask The bitmask of comparison flags. See `baseIsEqual` * for more details. * @param {Object} stack Tracks traversed `object` and `other` objects. * @returns {boolean} Returns `true` if the objects are equivalent, else `false`. */ //比较toStringTag相等的两个对象是否相等 function equalByTag(object, other, tag, equalFunc, customizer, bitmask, stack) { switch (tag) { case dataViewTag://'[object DataView]' if ((object.byteLength != other.byteLength) || (object.byteOffset != other.byteOffset)) { return false; } object = object.buffer; other = other.buffer; case arrayBufferTag://'[object ArrayBuffer]' if ((object.byteLength != other.byteLength) || !equalFunc(new Uint8Array(object), new Uint8Array(other))) { return false; } return true; case boolTag://'[object Boolean]' case dateTag://'[object Date]' case numberTag://'[object Number]' // Coerce booleans to `1` or `0` and dates to milliseconds. // Invalid dates are coerced to `NaN`. //强制转换布尔值到1或0，时间对象转换为毫秒，无效的时间转换为NaN return eq(+object, +other); case errorTag://'[object Error]' return object.name == other.name && object.message == other.message; case regexpTag://'[object RegExp]' case stringTag://'[object String]' // Coerce regexes to strings and treat strings, primitives and objects, // as equal. See http://www.ecma-international.org/ecma-262/7.0/#sec-regexp.prototype.tostring // for more details. return object == (other + ''); case mapTag://'[object Map]' var convert = mapToArray; //将map转换成数组的方法 /* {key1: value1, key2: value2, ...} 变成： [[key1, value1], [key2, value2], ...] */ case setTag://'[object Set]' var isPartial = bitmask & PARTIAL_COMPARE_FLAG;//是否部分比较 convert || (convert = setToArray);//将map或者set转换成数组的方法，mapToArray或者setToArray if (object.size != other.size && !isPartial) {//如果不是部分比较，且长度不一样，直接返回false return false; } // Assume cyclic values are equal. //假设循环值都相等，从中判断不相等的情况 var stacked = stack.get(object); if (stacked) {//防止循环引用 return stacked == other; } bitmask |= UNORDERED_COMPARE_FLAG; // Recursively compare objects (susceptible to call stack limits). //继续递归比较对象 stack.set(object, other); var result = equalArrays(convert(object), convert(other), equalFunc, customizer, bitmask, stack); stack['delete'](object); return result; case symbolTag://'[object Symbol]' if (symbolValueOf) {//Symbol.prototype.valueOf return symbolValueOf.call(object) == symbolValueOf.call(other); } } return false; } /** * A specialized version of `baseIsEqualDeep` for objects with support for * partial deep comparisons. * * @private * @param {Object} object The object to compare. * @param {Object} other The other object to compare. * @param {Function} equalFunc The function to determine equivalents of values. * @param {Function} customizer The function to customize comparisons. * @param {number} bitmask The bitmask of comparison flags. See `baseIsEqual` * for more details. * @param {Object} stack Tracks traversed `object` and `other` objects. * @returns {boolean} Returns `true` if the objects are equivalent, else `false`. */ //判断object类型深度比较是否相等，支持部分比较 function equalObjects(object, other, equalFunc, customizer, bitmask, stack) { var isPartial = bitmask & PARTIAL_COMPARE_FLAG,//是否部分比较 objProps = keys(object),//Object.keys()，返回key组成的数组 objLength = objProps.length, othProps = keys(other),//Object.keys()，返回key组成的数组 othLength = othProps.length; if (objLength != othLength && !isPartial) {//如果不是部分比较，且object和other的key长度不一样，返回false return false; } var index = objLength;//循环索引是object key数组的长度 while (index--) { var key = objProps[index];//object 的key if (!(isPartial ? key in other : hasOwnProperty.call(other, key))) { //如果是部分比较，就用in来判断，否则用Object.prototype.hasOwnProperty //判断object的key是否other里也有 //如果没有，返回false return false; } } // Assume cyclic values are equal. var stacked = stack.get(object); if (stacked && stack.get(other)) {//判断循环引用的情况 return stacked == other; } var result = true;//开始循环之前假设循环的值都是相等的 stack.set(object, other); stack.set(other, object); var skipCtor = isPartial;;//部分比较，跳过constructor while (++index < objLength) { key = objProps[index];//object的key var objValue = object[key],//object key对应的value othValue = other[key];//other key对应的value if (customizer) {//如果有自定义比较方法，就用自定义的比较 var compared = isPartial ? customizer(othValue, objValue, key, other, object, stack) : customizer(objValue, othValue, key, object, other, stack); } // Recursively compare objects (susceptible to call stack limits). if (!(compared === undefined ? (objValue === othValue || equalFunc(objValue, othValue, customizer, bitmask, stack)) : compared )) {//如果自定义比较失败就跳出循环，result=false //如果不是自定义比较，就用===比较，或者继续递归调用baseIsEqual来深度比较 result = false; break; } skipCtor || (skipCtor = key == 'constructor'); } if (result && !skipCtor) {//不是部分比较且object中有constructor属性，不跳过constructor属性，判断constructor是否一样 var objCtor = object.constructor, othCtor = other.constructor; // Non `Object` object instances with different constructors are not equal. if (objCtor != othCtor && ('constructor' in object && 'constructor' in other) && !(typeof objCtor == 'function' && objCtor instanceof objCtor && typeof othCtor == 'function' && othCtor instanceof othCtor)) { result = false; } } stack['delete'](object); stack['delete'](other); return result; } /** * Gets the data for `map`. * * @private * @param {Object} map The map to query. * @param {string} key The reference key. * @returns {*} Returns the map data. */ function getMapData(map, key) { var data = map.__data__; return isKeyable(key) ? data[typeof key == 'string' ? 'string' : 'hash'] : data.map; } /** * Gets the native function at `key` of `object`. * * @private * @param {Object} object The object to query. * @param {string} key The key of the method to get. * @returns {*} Returns the function if it's native, else `undefined`. */ function getNative(object, key) { var value = getValue(object, key); return baseIsNative(value) ? value : undefined; } /** * Gets the `toStringTag` of `value`. * * @private * @param {*} value The value to query. * @returns {string} Returns the `toStringTag`. */ var getTag = baseGetTag; // Fallback for data views, maps, sets, and weak maps in IE 11, // for data views in Edge < 14, and promises in Node.js. if ((DataView && getTag(new DataView(new ArrayBuffer(1))) != dataViewTag) || (Map && getTag(new Map) != mapTag) || (Promise && getTag(Promise.resolve()) != promiseTag) || (Set && getTag(new Set) != setTag) || (WeakMap && getTag(new WeakMap) != weakMapTag)) { getTag = function(value) { var result = objectToString.call(value), Ctor = result == objectTag ? value.constructor : undefined, ctorString = Ctor ? toSource(Ctor) : undefined; if (ctorString) { switch (ctorString) { case dataViewCtorString: return dataViewTag; case mapCtorString: return mapTag; case promiseCtorString: return promiseTag; case setCtorString: return setTag; case weakMapCtorString: return weakMapTag; } } return result; }; } /** * Checks if `value` is a valid array-like index. * * @private * @param {*} value The value to check. * @param {number} [length=MAX_SAFE_INTEGER] The upper bounds of a valid index. * @returns {boolean} Returns `true` if `value` is a valid index, else `false`. */ function isIndex(value, length) { length = length == null ? MAX_SAFE_INTEGER : length; return !!length && (typeof value == 'number' || reIsUint.test(value)) && (value > -1 && value % 1 == 0 && value < length); } /** * Checks if `value` is suitable for use as unique object key. * * @private * @param {*} value The value to check. * @returns {boolean} Returns `true` if `value` is suitable, else `false`. */ function isKeyable(value) { var type = typeof value; return (type == 'string' || type == 'number' || type == 'symbol' || type == 'boolean') ? (value !== '__proto__') : (value === null); } /** * Checks if `func` has its source masked. * * @private * @param {Function} func The function to check. * @returns {boolean} Returns `true` if `func` is masked, else `false`. */ function isMasked(func) { return !!maskSrcKey && (maskSrcKey in func); } /** * Checks if `value` is likely a prototype object. * * @private * @param {*} value The value to check. * @returns {boolean} Returns `true` if `value` is a prototype, else `false`. */ function isPrototype(value) { var Ctor = value && value.constructor, proto = (typeof Ctor == 'function' && Ctor.prototype) || objectProto; return value === proto; } /** * Converts `func` to its source code. * * @private * @param {Function} func The function to process. * @returns {string} Returns the source code. */ function toSource(func) { if (func != null) { try { return funcToString.call(func); } catch (e) {} try { return (func + ''); } catch (e) {} } return ''; } /** * Performs a * [`SameValueZero`](http://ecma-international.org/ecma-262/7.0/#sec-samevaluezero) * comparison between two values to determine if they are equivalent. * * @static * @memberOf _ * @since 4.0.0 * @category Lang * @param {*} value The value to compare. * @param {*} other The other value to compare. * @returns {boolean} Returns `true` if the values are equivalent, else `false`. * @example * * var object = { 'a': 1 }; * var other = { 'a': 1 }; * * _.eq(object, object); * // => true * * _.eq(object, other); * // => false * * _.eq('a', 'a'); * // => true * * _.eq('a', Object('a')); * // => false * * _.eq(NaN, NaN); * // => true */ function eq(value, other) { return value === other || (value !== value && other !== other); } /** * Checks if `value` is likely an `arguments` object. * * @static * @memberOf _ * @since 0.1.0 * @category Lang * @param {*} value The value to check. * @returns {boolean} Returns `true` if `value` is an `arguments` object, * else `false`. * @example * * _.isArguments(function() { return arguments; }()); * // => true * * _.isArguments([1, 2, 3]); * // => false */ function isArguments(value) { // Safari 8.1 makes `arguments.callee` enumerable in strict mode. return isArrayLikeObject(value) && hasOwnProperty.call(value, 'callee') && (!propertyIsEnumerable.call(value, 'callee') || objectToString.call(value) == argsTag); } /** * Checks if `value` is classified as an `Array` object. * * @static * @memberOf _ * @since 0.1.0 * @category Lang * @param {*} value The value to check. * @returns {boolean} Returns `true` if `value` is an array, else `false`. * @example * * _.isArray([1, 2, 3]); * // => true * * _.isArray(document.body.children); * // => false * * _.isArray('abc'); * // => false * * _.isArray(_.noop); * // => false */ var isArray = Array.isArray; /** * Checks if `value` is array-like. A value is considered array-like if it's * not a function and has a `value.length` that's an integer greater than or * equal to `0` and less than or equal to `Number.MAX_SAFE_INTEGER`. * * @static * @memberOf _ * @since 4.0.0 * @category Lang * @param {*} value The value to check. * @returns {boolean} Returns `true` if `value` is array-like, else `false`. * @example * * _.isArrayLike([1, 2, 3]); * // => true * * _.isArrayLike(document.body.children); * // => true * * _.isArrayLike('abc'); * // => true * * _.isArrayLike(_.noop); * // => false */ function isArrayLike(value) { return value != null && isLength(value.length) && !isFunction(value); } /** * This method is like `_.isArrayLike` except that it also checks if `value` * is an object. * * @static * @memberOf _ * @since 4.0.0 * @category Lang * @param {*} value The value to check. * @returns {boolean} Returns `true` if `value` is an array-like object, * else `false`. * @example * * _.isArrayLikeObject([1, 2, 3]); * // => true * * _.isArrayLikeObject(document.body.children); * // => true * * _.isArrayLikeObject('abc'); * // => false * * _.isArrayLikeObject(_.noop); * // => false */ function isArrayLikeObject(value) { return isObjectLike(value) && isArrayLike(value); } /** * Performs a deep comparison between two values to determine if they are * equivalent. * * **Note:** This method supports comparing arrays, array buffers, booleans, * date objects, error objects, maps, numbers, `Object` objects, regexes, * sets, strings, symbols, and typed arrays. `Object` objects are compared * by their own, not inherited, enumerable properties. Functions and DOM * nodes are **not** supported. * * @static * @memberOf _ * @since 0.1.0 * @category Lang * @param {*} value The value to compare. * @param {*} other The other value to compare. * @returns {boolean} Returns `true` if the values are equivalent, else `false`. * @example * * var object = { 'a': 1 }; * var other = { 'a': 1 }; * * _.isEqual(object, other); * // => true * * object === other; * // => false */ //对两个值执行深度比较来确定是否它们是相等的 //注意：此方法支持比较arrays, array buffers, booleans, date objects, error objects, maps, numbers, `Object` objects, regexes, sets, strings, symbols, typed arrays。Object对象会比较它们自身非继承可枚举的属性。不支持function和DOM节点的比较 function isEqual(value, other) { return baseIsEqual(value, other); } /** * Checks if `value` is classified as a `Function` object. * * @static * @memberOf _ * @since 0.1.0 * @category Lang * @param {*} value The value to check. * @returns {boolean} Returns `true` if `value` is a function, else `false`. * @example * * _.isFunction(_); * // => true * * _.isFunction(/abc/); * // => false */ function isFunction(value) { // The use of `Object#toString` avoids issues with the `typeof` operator // in Safari 8-9 which returns 'object' for typed array and other constructors. var tag = isObject(value) ? objectToString.call(value) : ''; return tag == funcTag || tag == genTag; } /** * Checks if `value` is a valid array-like length. * * **Note:** This method is loosely based on * [`ToLength`](http://ecma-international.org/ecma-262/7.0/#sec-tolength). * * @static * @memberOf _ * @since 4.0.0 * @category Lang * @param {*} value The value to check. * @returns {boolean} Returns `true` if `value` is a valid length, else `false`. * @example * * _.isLength(3); * // => true * * _.isLength(Number.MIN_VALUE); * // => false * * _.isLength(Infinity); * // => false * * _.isLength('3'); * // => false */ function isLength(value) { return typeof value == 'number' && value > -1 && value % 1 == 0 && value <= MAX_SAFE_INTEGER; } /** * Checks if `value` is the * [language type](http://www.ecma-international.org/ecma-262/7.0/#sec-ecmascript-language-types) * of `Object`. (e.g. arrays, functions, objects, regexes, `new Number(0)`, and `new String('')`) * * @static * @memberOf _ * @since 0.1.0 * @category Lang * @param {*} value The value to check. * @returns {boolean} Returns `true` if `value` is an object, else `false`. * @example * * _.isObject({}); * // => true * * _.isObject([1, 2, 3]); * // => true * * _.isObject(_.noop); * // => true * * _.isObject(null); * // => false */ function isObject(value) { var type = typeof value; return !!value && (type == 'object' || type == 'function'); } /** * Checks if `value` is object-like. A value is object-like if it's not `null` * and has a `typeof` result of "object". * * @static * @memberOf _ * @since 4.0.0 * @category Lang * @param {*} value The value to check. * @returns {boolean} Returns `true` if `value` is object-like, else `false`. * @example * * _.isObjectLike({}); * // => true * * _.isObjectLike([1, 2, 3]); * // => true * * _.isObjectLike(_.noop); * // => false * * _.isObjectLike(null); * // => false */ function isObjectLike(value) { return !!value && typeof value == 'object'; } /** * Checks if `value` is classified as a typed array. * * @static * @memberOf _ * @since 3.0.0 * @category Lang * @param {*} value The value to check. * @returns {boolean} Returns `true` if `value` is a typed array, else `false`. * @example * * _.isTypedArray(new Uint8Array); * // => true * * _.isTypedArray([]); * // => false */ var isTypedArray = nodeIsTypedArray ? baseUnary(nodeIsTypedArray) : baseIsTypedArray; /** * Creates an array of the own enumerable property names of `object`. * * **Note:** Non-object values are coerced to objects. See the * [ES spec](http://ecma-international.org/ecma-262/7.0/#sec-object.keys) * for more details. * * @static * @since 0.1.0 * @memberOf _ * @category Object * @param {Object} object The object to query. * @returns {Array} Returns the array of property names. * @example * * function Foo() { * this.a = 1; * this.b = 2; * } * * Foo.prototype.c = 3; * * _.keys(new Foo); * // => ['a', 'b'] (iteration order is not guaranteed) * * _.keys('hi'); * // => ['0', '1'] */ function keys(object) { return isArrayLike(object) ? arrayLikeKeys(object) : baseKeys(object); } module.exports = isEqual;