1、判断是否是一个数
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function
isArray(arr){
return
Object.prototype.toString.call(arr) ===
'[object Array]'
;
}
isArray([1,2,3])
//true
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2、判断是否是一个函数(三种)
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function
isFunction(fn) {
return
Object.prototype.toString.call(fn) ===
'[object Function]'
;
return
fn.constructor == Function;
return
fn
instanceof
Function;
return
typeof
(fn) == Function;
}
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3、数组去重，只考虑数组中元素为数字或者字符串
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function
newarr(arr){
var
arrs = [];
for
(
var
i =0;i<arr.length;i++){
if
(arrs.indexOf(arr[i])== -1){
arrs.push(arr[i])
}
}
return
arrs;
}
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4、动态去重
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var
arr = [1,2, 3, 4];
function
add() {
var
newarr = [];
$(
'.addEle'
).click(() => {
var
rnd = Math.ceil(Math.random() * 10);
newarr.push(rnd)
for
(
var
i =0; i < newarr.length; i++) {
if
(arr.indexOf(newarr[i]) == -1) {
arr.push(newarr[i])
arr.sort(
function
(a, b) {
return
b - a
//降序
});
}
}
console.log(arr)
//[1,2,3,4,5,6,7,8,9]
})
}
add()
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5、去除字符串空格(包含三种情况)
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function
trim(str) {
return
str.replace(/^[
" "
||
" "
]*/,
""
).replace(/[
" "
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" "
]*$/,
""
);
// 去除头和尾
return
str.replace(/\s/g,
''
);
//去除所有空格
return
str.replace(/(\s*$)/g,
""
);
//去除右边所有空格
}
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6、判断是否为邮箱地址
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function
isEmail(emailStr) {
var
reg = /^[a-zA-Z0-9]+([._-]*[a-zA-Z0-9]*)*@[a-zA-Z0-9]+.[a-zA-Z0-9{2,5}$]/;
var
result = reg.test(emailStr);
if
(result) {
alert(
"ok"
);
}
else
{
alert(
"error"
);
}
}
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7、判断是否是手机号
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function
isMobilePhone(phone) {
var
reg = /^1\d{10}$/;
if
(reg.test(phone)) {
alert(
'ok'
);
}
else
{
alert(
'error'
);
}
}
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8、获取一个对象里面第一次元素的数量
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function
getObjectLength(obj){
var
i=0;
for
(
var
attrin obj){
if
(obj.hasOwnProperty(attr)){
i++;
}
}
console.log(i);
}
var
obj = {name:
'kob'
,age:20};
getObjectLength(obj)
//2
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9、获取元素相对于浏览器窗口的位置，返回一个{x,y}对象
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function
getPosition(element) {
var
offsety = 0;
offsety += element.offsetTop;
var
offsetx = 0;
offsetx += element.offsetLeft;
if
(element.offsetParent !=
null
) {
getPosition(element.offsetParent);
}
return
{ Left: offsetx, Top: offsety };
}
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10、判断某个字母在字符串中出现的次数
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var
str =
'To be, or not to be, that is the question.'
;
var
count = 0;
var
pos = str.indexOf(
'e'
);
while
(pos !== -1) {
count++;
pos = str.indexOf(
'e'
, pos + 1);
}
console.log(count)
//4
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11、计算出数组中出现次数最多的元素
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var
arrayObj = [1,1, 2, 3, 3, 3,4, 5, 5];
var
tepm =
''
,count =0;
var
newarr =
new
Array();
for
(
var
i=0;i<arrayObj.length;i++){
if
(arrayObj[i] != -1) {
temp = arrayObj[i];
}
for
(
var
j=0;j<arrayObj.length;j++){
if
(temp == arrayObj[j]) {
count++;
arrayObj[j] = -1;
}
}
newarr.push(temp +
":"
+ count);
count = 0;
}
for
(
var
i=0;i<newarr.length;i++){
console.log(newarr[i]);
}
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12、数组filter（搜索功能）
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var
fruits = [
'apple'
,
'banana'
,
'grapes'
,
'mango'
,
'orange'
];
function
filterItems(query) {
return
fruits.filter(
function
(el) {
return
el.toLowerCase().indexOf(query.toLowerCase()) > -1;
})
}
console.log(filterItems(
'ap'
));
// ['apple', 'grapes']
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13、copy 对象（第一种）
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//第一种
var
cloneObj =
function
(obj) {
var
newObj = {};
if
(obj
instanceof
Array) {
newObj = [];
}
for
(
var
keyin obj) {
var
val = obj[key];
newObj[key] =
typeof
val ===
'object'
? cloneObj(val) : val;
}
return
newObj;
};
//第二种
function
clone(origin , target){
var
target = target || {};
for
(
var
propin origin){
target[prop] = origin[prop];
}
return
target;
}
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14、深度克隆
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var
newObj ={};
function
deepClone(origin,target){
var
target = target || {},
toStr = Object.prototype.toString,
arrStr =
"[object Array]"
;
for
(
var
propin origin){
if
(origin.hasOwnProperty(prop)){
if
(origin[prop] !=
"null"
&&
typeof
(origin[prop]) ==
'object'
){
//判断原型链
target[prop] = (toStr.call(origin[prop]) == arrStr) ? [] : {}
//判断obj的key是否是数组
deepClone(origin[prop],target[prop]);
//递归的方式
}
else
{
target[prop] = origin[prop];
}
}
}
return
target
}
deepClone(obj,newObj);
console.log(newObj)
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15、求数组最大值和最小值
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Array.prototype.max =
function
(){
return
Math.max.apply({},
this
)
}
Array.prototype.min =
function
(){
return
Math.min.apply({},
this
)
}
console.log([1,5,2].max())
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16、json数组去重
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function
UniquePay(paylist){
var
payArr = [paylist[0]];
for
(
var
i =1; i < paylist.length; i++){
var
payItem = paylist[i];
var
repeat =
false
;
for
(
var
j =0; j < payArr.length; j++) {
if
(payItem.name == payArr[j].name) {
repeat =
true
;
break
;
}
}
if
(!repeat) {
payArr.push(payItem);
}
}
return
payArr;
}
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17、对比两个数组，取出交集
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Array.intersect =
function
() {
var
result =
new
Array();
var
obj = {};
for
(
var
i =0; i < arguments.length; i++) {
for
(
var
j =0; j < arguments[i].length; j++) {
var
str = arguments[i][j];
if
(!obj[str]) {
obj[str] = 1;
}
else
{
obj[str]++;
if
(obj[str] == arguments.length)
{
result.push(str);
}
}
//end else
}
//end for j
}
//end for i
return
result;
}
console.log(Array.intersect([
"1"
,
"2"
,
"3"
], [
"2"
,
"3"
,
"4"
,
"5"
,
"6"
]))
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18、数组和对象比较。取出对象的key和数组元素相同的
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var
arr = [
'F00006'
,
'F00007'
,
'F00008'
];
var
obj = {
'F00006'
:[{
'id'
:21}],
'F00007'
:[{
'id'
:11}]}
var
newobj = {};
for
(
var
itemin obj){
if
(arr.includes(item)){
newobj[item] = obj[item]
}
}
console.log(newObj)
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19、删除数组中某个元
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//第一种
Array.prototype.remove =
function
(val){
var
index =
this
.indexOf(val);
if
(index !=0){
this
.splice(index,1)
}
}
[1,3,4].remove(3)
//第二种
function
remove(arr, indx) {
for
(
var
i =0; i < arr.length; i++) {
var
index = arr.indexOf(arr[i]);
if
(indx == index) {
arr.splice(index, 1)
}
}
return
arr
}
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20、判断数组是否包含某个元素
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Array.prototype.contains =
function
(val) {
for
(
var
i =0; i <
this
.length; i++) {
if
(
this
[i] == val) {
return
true
;
}
}
return
false
;
};
[1, 2,3, 4].contains(2)
//true
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