javascript 常用函數

 

 

/**
獲取元素到頁面頂端的距離(出自jquery源碼)
 */
function getCoords(el) {

    if (typeof el == 'string') {
        el = Fid(el);
    }

    var box = el.getBoundingClientRect(),
    doc = el.ownerDocument,
    body = doc.body,
    html = doc.documentElement,
    clientTop = html.clientTop || body.clientTop || 0,
    clientLeft = html.clientLeft || body.clientLeft || 0,
    top = box.top + (self.pageYOffset || html.scrollTop || body.scrollTop) - clientTop,
    left = box.left + (self.pageXOffset || html.scrollLeft || body.scrollLeft) - clientLeft
        return {
        'top' : top,
        'left' : left
    };
};

/*
獲取元素到頁面頂端的
document.documentElement.clientLeft ie6/7 下2px的bodrer
 */
function getAbsPoint(e) {

    if (typeof e == 'string') {
        e = Fid(e);
    }

    var x = e.offsetLeft;
    var y = e.offsetTop;
    var de = document.documentElement;
    while (e = e.offsetParent) { //在IE下offset對象是對當前元素到上一級元素的距離,FF則是正常的
        x += e.offsetLeft;
        y += e.offsetTop;

        //需要加上元素自身的border, offsetTop 本身就包含margin
        if (e && e != de && !Browser.isOpera) {
            x += e.clientLeft;
            y += e.clientTop; //ie6下設置元素寬度后才能到獲取他的邊框大小,如果不設置則下級取上級的時候會把上級的邊框算進去(總體計算還是沒有錯)
        }
    }
    return {
        "left" : x,
        "top" : y
    };
}

 

//瀏覽器類型檢測
var FBrowser=(function(){
    var ua = navigator.userAgent;
    var isOpera = Object.prototype.toString.call(window.opera) == '[object Opera]';
    return {
      isIE:             !!window.attachEvent && window.ActiveXObject && !isOpera,
      isOpera:          isOpera,
      isSafari:         ua.indexOf('AppleWebKit/') > -1,
      isFirefox:        ua.indexOf('Gecko') > -1 && ua.indexOf('KHTML') === -1,
      MobileSafari:     /Apple.*Mobile.*Safari/.test(ua),
      isChrome:         !!window.chrome,

    };
})();

FBrowser.isIE6=FBrowser.isIE&&!window.XMLHttpRequest;
FBrowser.isIE7=FBrowser.isIE&&!!window.XMLHttpRequest;

 

//document.documentMode ie8+以上顯示瀏覽器版本
var IE = (function(){
    var ie =  !!window.ActiveXObject;
         e = {
            isIE: !!window.ActiveXObject,
            isIE6: ie && !window.XMLHttpRequest,
            isIE7: ie && window.XMLHttpRequest && document.documentMode == 7,
            isIE8: ie && window.XMLHttpRequest && document.documentMode == 8,
            isIE9: ie && window.XMLHttpRequest && document.documentMode == 9
         }
    return e;
    })();

 

 

/**
獲取元素樣式
處理透明度、元素浮動樣式的獲取 ，結果帶有單位
*/
function getStyle(elem, name) {
    var nameValue = null;
    if (document.defaultView) {
        var style = document.defaultView.getComputedStyle(elem, null);
        nameValue =  name in style ? style[name] : style.getPropertyValue(name);
    } else {
        var style = elem.style,
        curStyle = elem.currentStyle;
        //透明度 from youa
        if (name == "opacity") {
            if (/alpha\(opacity=(.*)\)/i.test(curStyle.filter)) {
                var opacity = parseFloat(RegExp.$1);
                
                return opacity ? opacity / 100 : 0;
            }
            return 1;
        }
        if (name == "float") {
            name = "styleFloat";
        }
        var ret = curStyle[name] || curStyle[camelize(name)];
        //單位轉換 from jqury
        if (!/^-?\d+(?:px)?$/i.test(ret) && /^\-?\d/.test(ret)) {
            var left = style.left,
            rtStyle = elem.runtimeStyle,
            rsLeft = rtStyle.left;

            rtStyle.left = curStyle.left;
            style.left = ret || 0;
            ret = style.pixelLeft + "px";

            style.left = left;
            rtStyle.left = rsLeft;
        }
        
        nameValue = ret;
    }
    
    return nameValue === 'auto' ? '0px' : nameValue;
}

function uncamelize(s) {//將CSS屬性名由駝峰式轉為普通式
    return s.replace(/[A-Z]/g,function (c) {
        return '-'+c.charAt(0).toLowerCase();
    });
}

function camelize(s) {//將CSS屬性名轉換成駝峰式
    return s.replace(/-[a-z]/gi,function (c) {
        return c.charAt(1).toUpperCase();
    });
}

 

function each( object, callback ) {
        if ( undefined === object.length ){
            for ( var name in object ) {
                if (false === callback( object[name], name, object )) break;
            }
        } else {
            for ( var i = 0, len = object.length; i < len; i++ ) {
                if (i in object) { if (false === callback( object[i], i, object )) break; }
            }
        }
    }

 

//獲取scrolltop
function getScrollTop()
{
    var scrollTop = document.documentElement.scrollTop || document.body.scrollTop;
    return     scrollTop;
}

//設置scrolltop
function setScrollTop(top)
{
    document.documentElement.scrollTop = document.body.scrollTop = top;
}

 

 

/**
獲取瀏覽器可視區域的尺寸
*/
function getBrowserSize()
{
    //在標准模式下用 documentElement， 在怪癖模式下用 body
    return {
        width:document.documentElement.clientWidth ? document.documentElement.clientWidth : document.body.clientWidth,
        height:document.documentElement.clientHeight ? document.documentElement.clientHeight : document.body.clientHeight,
    }
}

 

 

/**
獲取頁面大小
*/
function getPageSize()
{
    //ie下優先取 body
    return {
        width:document.body.scrollWidth ? document.body.scrollWidth : document.documentElement.scrollWidth,
        height: document.body.scrollHeight ? document.body.scrollHeight   : document.documentElement.scrollHeight
    }
}

 

 

/**
 * 根據類名獲取元素
 * 
 * @param className
 * @param context
 * @returns
 */
function getByClassName(className,context) {
    context=context || document;
    if (context.getElementsByClassName) {
        return context.getElementsByClassName(className);
    }
    var nodes=context.getElementsByTagName('*'),ret=[];
    for (var i=0;i<nodes.length;i++) {
        if (nodes[i].nodeType == 1 && nodes[i].className.indexOf(className) != -1)
        {
            ret.push(nodes[i]);
        }    
    }
    return ret;
}

 

 

/**
 * Registers a callback for DOM ready. If DOM is already ready, the
 * callback is called immediately.
 * @param {Function} Array callback
 */
function domReady(callback) {
    var isTop, testDiv, scrollIntervalId,
        isPageLoaded = false,
        doc = document,
        readyCalls = [];

    function runCallbacks(callbacks) {
        var i;
        for (i = 0; i < callbacks.length; i += 1) {
            callbacks[i](doc);
        }
    }

    function callReady() {
        var callbacks = readyCalls;

        if (isPageLoaded) {
            //Call the DOM ready callbacks
            if (callbacks.length) {
                readyCalls = [];
                runCallbacks(callbacks);
            }
        }
    }

    /**
     * Sets the page as loaded.
     */
    function pageLoaded() {
        if (!isPageLoaded) {
            isPageLoaded = true;
            if (scrollIntervalId) {
                clearInterval(scrollIntervalId);
            }

            callReady();
        }
    }
  
    if (document.addEventListener) {
        //Standards. Hooray! Assumption here that if standards based,
        //it knows about DOMContentLoaded.
        document.addEventListener("DOMContentLoaded", pageLoaded, false);
        window.addEventListener("load", pageLoaded, false);
    } else if (window.attachEvent) {
        window.attachEvent("onload", pageLoaded);

        testDiv = document.createElement('div');
        try {
            isTop = window.frameElement === null;
        } catch (e) {}

        //DOMContentLoaded approximation that uses a doScroll, as found by
        //Diego Perini: http://javascript.nwbox.com/IEContentLoaded/,
        //but modified by other contributors, including jdalton
        if (testDiv.doScroll && isTop && window.external) {
            scrollIntervalId = setInterval(function () {
                try {
                    testDiv.doScroll();
                    pageLoaded();
                } catch (e) {}
            }, 1);
        }
    }

    //Check if document already complete, and if so, just trigger page load
    //listeners. Latest webkit browsers also use "interactive", and
    //will fire the onDOMContentLoaded before "interactive" but not after
    //entering "interactive" or "complete". More details:
    //http://dev.w3.org/html5/spec/the-end.html#the-end
    //http://stackoverflow.com/questions/3665561/document-readystate-of-interactive-vs-ondomcontentloaded
    //Hmm, this is more complicated on further use, see "firing too early"
    //bug: https://github.com/requirejs/domReady/issues/1
    //so removing the || document.readyState === "interactive" test.
    //There is still a window.onload binding that should get fired if
    //DOMContentLoaded is missed.
    if (document.readyState === "complete") {
        pageLoaded();
    }
    
    if (isPageLoaded) {//dom已經ready
        callback(doc);
    } else {
        readyCalls.push(callback);
    }
}

domReady(function(){
    alert('domload');
    alert(document.getElementById('container'));
})

 

 

//改變某個函數的內部this指針
function closure(fn, scope)
{
    return function (){
        fn.apply(scope, arguments);
    };
}

//調用某個對象的某個函數，並將次對象作為方法的作用域
function invoke(obj, methodName)
{
    return function(){
        obj.methodName.apply(obj, arguments);
    };
}

 

 

// 元素數據緩存
(function(){
 
    var cache = [0],
        expando = 'data' + +new Date();
 
    function data(elem) {
 
        var cacheIndex = elem[expando],
            nextCacheIndex = cache.length;
 
        if(!cacheIndex) {
            cacheIndex = elem[expando] = nextCacheIndex;
            cache[cacheIndex] = {};
        }
 
        return {
            get : function(key) {
                if(typeof key === 'string')
                {
                     return cache[cacheIndex] ? cache[cacheIndex][key] : null;
                }
                return cache[cacheIndex] ? cache[cacheIndex] : null;
            },
            set : function(key, val) {
                cache[cacheIndex][key] = val;
                return data(elem);
            },
            remove : function(key){
                if(cache[cacheIndex])
                {
                    return cache.splice(cacheIndex,1);                    
                }
            }
        }
    }
 
    window.data = data;
 
})();

 

//js請求xml文件，
if (window.ActiveXObject) {
    //IE
    var getXMLDOM=function () {
        return new ActiveXObject("Microsoft.XmlDom");
    },loadXMLFile=function (xmlDom,url,callback) {
        xmlDom.onreadystatechange=function () {
            if (xmlDom.readyState===4) {
                if (xmlDom.parseError.errorCode===0) {
                    callback.call(xmlDom);
                } else {
                    throw new Error("XML Parse Error:"+xmlDom.parseError.reason);
                }
            }
        };
        xmlDom.load(url);
        return xmlDom;
    },loadXMLString=function (xmlDom,s) {
        xmlDom.loadXML(s);
        if (xmlDom.parseError.errorCode!==0) {
            throw new Error("XML Parse Error:"+xmlDom.parseError.reason);
        }
        return xmlDom;
    },
    getXML=function (xmlNode) {
        return xmlNode.xml;
    };
}else if (document.implementation && document.implementation.createDocument) {
    //W3C
    var getXMLDOM=function () {//獲取一個XMLDOM對象
        return document.implementation.createDocument("","",null);
    },
    loadXMLFile=function (xmlDom,url,callback) {
        if (xmlDom.async===true) {
            xmlDom.onload=function () {
                if (xmlDom.documentElement.nodeName=="parsererror") {
                    throw new Error("XML Parse Error:"+xmlDom.documentElement.firstChild.nodeValue);
                } else {
                    callback.call(xmlDom);
                }
            };
        }
        console.dir(xmlDom);
        xmlDom.load(url);
        return xmlDom;
    },
    loadXMLString=function (xmlDom,s) {
        var p = new DOMParser();
        var newDom=p.parseFromString(s,"text/xml");
        if (newDom.documentElement.nodeName=="parsererror") {
            throw new Error("XML Parse Error:"+newDom.documentElement.firstChild.nodeValue);
        }
        while (xmlDom.firstChild) {
            xmlDom.removeChild(xmlDom.firstChild);
        }
        for (var i=0,n;i<newDom.childNodes.length;i++) {
            n=xmlDom.importNode(newDom.childNodes[i],true);
            //importNode用於把其它文檔中的節點導入到當前文檔中
            //true參數同時導入子節點
            xmlDom.appendChild(n);
        }
        return xmlDom;
    },
    getXML=function (xmlNode) {
        var s= new XMLSerializer();
        return s.serializeToString(xmlNode,"text/xml");
    };
}

var xmldom = getXMLDOM();
loadXMLFile(xmldom,"/xml.php",function () {
   alert(this);
});

 

/**
args {
    url
    method 默認值為get
    success Function
    data {key:value}
    cache Boolean true表示緩存,默認值為false
    datatype 默認 text text|xml
}
*/
function ajax(args) {
    //創建xhr對象
    function createXHR() {
    return window.XMLHttpRequest?
        new XMLHttpRequest():
        new ActiveXObject("Microsoft.XMLHTTP");//IE6
    }
    
    //拼接參數    
    function params(o) {
        var a=[];
        for (var i in o) {
           a.push(encodeURIComponent(i)+"="+encodeURIComponent(o[i]));
        }
        return a.join("&");
    }
    
    var xhr = createXHR();
    
    args.method=args.method || "get";
    
    if (!args.cache) {
        args.data.cache = (new Date()*1);
    }
   
    var data_str = params(args.data)
    
    if (/get/i.test(args.method) && data_str) {
         args.url += args.url.indexOf("?")<0 ? '?' : '&';
         args.url += data_str;
    }
    
    xhr.open(args.method,args.url,true);
    
    xhr.onreadystatechange=function () {
        if (xhr.readyState===4 && xhr.status===200) {
            if(!args.datatype || args.datatype.toLowerCase() === 'text')
            {
                args.success(xhr.responseText);
            }else{
                args.success(xhr.responseXML);
            }
        }
    };
    
    if (/post/i.test(args.method)) {
        xhr.setRequestHeader("Content-Type","application/x-www-form-urlencoded");
        xhr.send(data);
    } else {
        xhr.send();
    }
}


ajax({
    url:"/xml.php",
    method:'post',
    success:function(xmldom){
        alert(xmldom.nodeName);
    },
    data:{id:1},
    datatype:'xml'
})

 

 

//獲取firstchild
function firstChild(elem)
{
    var node = elem.firstChild ? elem.firstChild : null;
    while(node && node.nodeType != 1)
    {
        node = node.nextSibling;
    }
    return node;
}

//獲取下一個同輩元素（ie下回忽略空白文節點）
function next(elem)
{
    var node = elem.nextSibling ? elem.nextSibling : null;
    while(node && node.nodeType != 1 )
    {
        node = node.nextSibling;
    }
    
    return node;
}

//獲取上一個同輩元素（ie下回忽略空白文節點）
function prev(elem)
{
    var node = elem.previousSibling ? elem.previousSibling : null;
    while(node && node.nodeType != 1 )
    {
        node = node.previousSibling;
    }
    
    return node;
}

 

/**
 * 獲取指定類名的父元素
 * @param elem
 * @param className
 * @returns
 */
function parents(elem, className)
{
    //檢測自身是否滿足條件
    if(elem.className.indexOf(className) != -1)
    {
        return elem;
    }    
    
    var parent = null;
    while((parent = elem.parentNode) &&  parent.nodeType == 1 && !!className)
    {
        if(parent.className.indexOf(className) != -1)
        {
            break;
        }
        elem = parent;
    }
    return parent;
}

 

 

//輸入html代碼，輸出轉換后的代碼
function htmlEncode( html )
{
    //使用div來模擬
    var div = document.createElement("div");
        
    if(typeof div.innerText != 'undefined')
    {
        div.innerText  = html;
    }else{
        div.textContent = html;
    }

    var html_encode = div.innerHTML;
    div = null;
    
    return html_encode;
}
function htmlDecode( html )
{
    //使用div來模擬
    var text, div = document.createElement("div");
    div.innerHTML = html;    
        
    if(typeof div.innerText != 'undefined')
    {
         text = div.innerText;
    }else{
        text = div.textContent;
    }
    
    return text;
}



function htmlEncode(str) {
    var s = "";
    if (str.length == 0) return "";
    s = str.replace(/\&/g, "&");
    s = s.replace(/</g, "&lt;");
    s = s.replace(/>/g, "&gt;");
    s = s.replace(/\'/g, "&#039;");
    s = s.replace(/\"/g, "&quot;");
    return s;
}
function htmlDecode(str) {
    var s = "";
    if (str.length == 0) return "";
    s = str.replace(/&amp;/g, "&");
    s = s.replace(/&lt;/g, "<");
    s = s.replace(/&gt;/g, ">");
    s = s.replace(/&#039;/g, "\'");
    s = s.replace(/&quot;/g, "\"");
    return s;
}



function htmlEncode(html)
{
  var div  = document.createElement("div");
  var text = document.createTextNode("");
  
  div.appendChild(text);
  
  text.nodeValue=html;
  return div.innerHTML;
}

function htmlDecode(str)
{
  var div  = document.createElement("div");
  div.innerHTML = str;
  
  return  div.firstChild.nodeValue;
}

 

//計算數組中的最大值
Array.prototype.max = function(){
 return Math.max.apply({},this)
}

//計算數組中的最小值
Array.prototype.min = function(){
 return Math.min.apply({},this)
}

//復制數組
Array.prototype.copy =
  function() {
    return [].concat(this);
};

//去除數組中只指定元素，只能去除一個，如果想多個，之前先用unique處理
Array.prototype.remove = function(value){
    for(var i=0,len=this.length;i<len;i++)
    {
        if(this[i]==value){
            this.splice(i, 1);
            break;
        }
    }
    
    return this;
}

//去除數組中只指定元素，只能去除一個，如果想多個，之前先用unique處理
Array.prototype.inArray = function(value){
    var index = -1;
    each(this,function(v,k){
        if(v == value){
            index = k;
            return false;
        }
    })

    return index;
}

//去除數組中的重復元素
Array.prototype.unique = function(){
    var rst = [];
    each(this, function(v,k){
        if(rst.inArray(v)<0) rst.push(v);
    })
    return rst;
}

 

String.prototype.repeat=function(n){return new Array(n+1).join(this);}

String.prototype.ltrim=function(){return this.replace(/^\s*/, "");}

String.prototype.rtrim=function(){return this.replace(/\s*$/, "");}

String.prototype.trim=function(){return this.rtrim().ltrim();}

//非ascii字符
String.prototype.hasChinese=function(){return /[^\u00-\uff]/g.test(this);}

//包括中英韓文，這三種語言里面有更多共同的
String.prototype.onlyChinese=function(){return /^[\u0391-\u9FBF]+$/g.test(this);}

//取得字符串實際長度(漢字算兩個字節,英文字母算一個字節) \x代表ascii碼，會按unicode碼進行匹配
String.prototype.bytes=function(){ return this.replace(/[^\x00-\xff]/gi,'xx').length;}

Number.prototype.inter=function (a,b) {//檢測數字是否在區間之內
    var min=Math.min(a,b),max=Math.max(a,b);
    return this==a || this==b || (Math.max(this,min)==this && Math.min(this,max)==this);
};

 

 

//過濾空白文本節點
function filterSpaceNode(nodes) {掉
    var ret=[];
    for(var i=0;i<nodes.length;i++) {
        if (nodes[i].nodeType===3 
                && /^\s+$/.test(nodes[i].nodeValue)) {
                    continue;
        }
        ret.push(nodes[i]);
    }
    return ret;
}

 

 

 

function addClassName(obj,cn) {
    return obj.className += " " + cn;
}

function delClassName(obj,cn) {
    return obj.className = obj.className.replace(new RegExp("\\b"+cn+"\\b"),"");
    //同樣，多個className之間的多個空格也會被視為一個
}

function hasClassName(obj,cn) {
    
        return (new RegExp("\\b"+cn+"\\b")).test(obj.className);
}

 

 

function placeNode(node,fn,__this) {
    fn.call(__this,frag(node));
    return __this;
}

function append(node, newNode) {
    return placeNode(newNode,function (one) {node.appendChild(one)},node);
}

function preappend(node, newNode) {
    return placeNode(newNode,function (one) {node.insertBefore(one,node.firstChild)},node);
}

function before(node, newNode) {
    return placeNode(newNode,function (one) {node.parentNode.insertBefore(one,node)},node);
}

function after(node, newNode) {
    //如果node有下一個節點的話,newNode 插入到node.nextSibling的前面
    //如果node沒有下一個節點,newNode插入為node.parentNode的最后一個子
    if (node.nextSibling) {
        placeNode(newNode,function (one) {node.parentNode.insertBefore(one,node.nextSibling)},node);
    } else {
        placeNode(newNode,function (one) {node.parentNode.appendChild(one)},node);
    }
    return node;
}

//如果新節點是頁面中已經存在的則新節點原來的位置會消失
function replaceNode(newNode, node) {
   node.parentNode.replaceChild(newNode, node);
}

function delNode(node) {
    node.parentNode.removeChild(this);
}

function frag(nodes) {
    var tempFrag =document.createDocumentFragment();
    if (nodes.nodeType) {nodes=[nodes];}
    
    /*    錯誤的寫法 傳入的是引用
    each(nodes,function(node){
        tempFrag.appendChild(node);
    })*/
    
    for(var i=0;i<nodes.length;i++) {
        //克隆后不在是引用
        var a = nodes[i].cloneNode(true);
        (function(node){
            tempFrag.appendChild(node);
        })(a)
    }
    
    /*    
        while(nodes.length>0)
        {
            tempFrag.appendChild(nodes[0]);
            alert(nodes.length);
        }
    */
    
    return tempFrag;
}

//html轉換為對象
function html2Obj(html)
{
    var div = document.createElement('div');
    div.innerHTML = html;
    return div.firstChild;
}

 

 

//數據的本地化存儲，都兼容
function makeWebStorage() {
    
    //ie用userdata實現，w3c瀏覽器本身支持
    if (!("localStorage" in window)) {
        var store = {
            userData : null,
            name : location.hostname,

            init : function () {
                if (!store.userData) {
                    try {
                        store.userData = document.createElement('INPUT');
                        store.userData.type = "hidden";
                        store.userData.style.display = "none";
                        store.userData.addBehavior("#default#userData");
                        document.body.appendChild(store.userData);
                        var expires = new Date();
                        expires.setDate(expires.getDate() + 365);
                        store.userData.expires = expires.toUTCString();
                    } catch (e) {
                        return false;
                    }
                }
                return true;
            },

            setItem : function (key, value) {

                if (store.init()) {
                    store.userData.load(store.name);
                    store.userData.setAttribute(key, value);
                    store.userData.save(store.name);
                }
            },

            getItem : function (key) {
                if (store.init()) {
                    store.userData.load(store.name);
                    return store.userData.getAttribute(key)
                }
            },

            remove : function (key) {
                if (store.init()) {
                    store.userData.load(store.name);
                    store.userData.removeAttribute(key);
                    store.userData.save(store.name);
                }

            }
        };
    }else{
        store = {
            set:function(key, value){localStorage.setItem(key, value)},
            get:function(key){return localStorage.getItem(key)},
            remove:function(key){return localStorage.removeItem(key)}
        }
    }

    window.webStorage = store;
}

 

 

/**
 * 記錄函數調用的次數
 */
function invokeTimes(){

    if(arguments.callee.times == undefined)
    {
        arguments.callee.times = 0;
    }
    arguments.callee.times ++;
    
    console.log(arguments.callee.times);
    
}
document.body.onclick = function(){
    
    invokeTimes();
}

 

 

/**
 *javascript按字節進行截取
 *
 * param str 要截取的字符串
 * param L 要截取的字節長度，注意是字節不是字符，一個漢字兩個字節
 * return 截取后的字符串
 */
function cutStr(str,L){    
    var result = '',
        strlen = str.length, // 字符串長度
        chrlen = str.replace(/[^\x00-\xff]/g,'**').length; // 字節長度

    if(chrlen<=L){return str;}
    
    for(var i=0,j=0;i<strlen;i++){
        var chr = str.charAt(i);
        if(/[\x00-\xff]/.test(chr)){
            j++; // ascii碼為0-255，一個字符就是一個字節的長度
        }else{
            j+=2; // ascii碼為0-255以外，一個字符就是兩個字節的長度
        }
        if(j<=L /* || j==L+1 */){ // 當加上當前字符以后，如果總字節長度小於等於L，則將當前字符真實的+在result后
            result += chr;
        }else{ // 反之則說明result已經是不拆分字符的情況下最接近L的值了，直接返回
            return result;
        }
    }
}

// 用例
alert(cutStr("abc中英文混合",10));

 

 

//變量定義 效果同php中的define函數
function define (name, value) {
  // Define a new constant
  //
  // version: 903.3016
  // discuss at: http://phpjs.org/functions/define
  // +      original by: Paulo Freitas
  // +       revised by: Andrea Giammarchi (http://webreflection.blogspot.com)
  // + reimplemented by: Brett Zamir (http://brett-zamir.me)
  // *        example 1: define('IMAGINARY_CONSTANT1', 'imaginary_value1');
  // *        results 1: IMAGINARY_CONSTANT1 === 'imaginary_value1'
  var defn, replace, script, that = this,
    d = this.window.document;
  var toString = function (name, value) {
    return 'const ' + name + '=' + (/^(null|true|false|(\+|\-)?\d+(\.\d+)?)$/.test(value = String(value)) ? value : '"' + replace(value) + '"');
  };
  try {
    eval('const e=1');
    replace = function (value) {
      var replace = {
        "\x08": "b",
        "\x0A": "\\n",
        "\x0B": "v",
        "\x0C": "f",
        "\x0D": "\\r",
        '"': '"',
        "\\": "\\"
      };
      return value.replace(/\x08|[\x0A-\x0D]|"|\\/g, function (value) {
        return "\\" + replace[value];
      });
    };
    defn = function (name, value) {
      if (d.createElementNS) {
        script = d.createElementNS('http://www.w3.org/1999/xhtml', 'script');
      } else {
        script = d.createElement('script');
      }
      script.type = 'text/javascript';
      script.appendChild(d.createTextNode(toString(name, value)));
      d.documentElement.appendChild(script);
      d.documentElement.removeChild(script);
    };
  } catch (e) {
    replace = function (value) {
      var replace = {
        "\x0A": "\\n",
        "\x0D": "\\r"
      };
      return value.replace(/"/g, '""').replace(/\n|\r/g, function (value) {
        return replace[value];
      });
    };
    defn = (this.execScript ?
    function (name, value) {
      that.execScript(toString(name, value), 'VBScript');
    } : function (name, value) {
      eval(toString(name, value).substring(6));
    });
  }
  defn(name, value);
}