自己整理的一些开发时候常用的js方法封装

1、判断是否是一个数组

function isArray(arr){

return Object.prototype.toString.call(arr) === '[object Array]';

}

isArray([1,2,3]) //true

2、判断是否是一个函数(三种)

function isFunction(fn) {

return Object.prototype.toString.call(fn) === '[object Function]';

return fn.constructor == Function;

return fn instanceof Function;

return typeof (fn) == Function;

}

3、数组去重，只考虑数组中元素为数字或者字符串

function newarr(arr){

var arrs = [];

for( var i = 0;i

if(arrs.indexOf(arr[i])== - 1){

arrs.push(arr[i])

}

}

return arrs;

}

4、动态去重

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()

5、去除字符串空格(包含三种情况)

function trim(str) {

return str.replace( / ^ [" "||"　"]* /, "").replace( /[" "|"　"]* $ /, ""); // 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

}

6、判断是否为邮箱地址

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");

}

}

7、判断是否是手机号

function isMobilePhone(phone) {

var reg = / ^ 1\d{10} $ /;

if (reg.test(phone)) {

alert( 'ok');

} else {

alert( 'error');

}

}

8、获取一个对象里面第一次元素的数量

function getObjectLength(obj){

var i= 0;

for( var attr in obj){

if(obj.hasOwnProperty(attr)){

i++;

}

}

console.log(i);

}

var obj = {name:'kob',age:20};
getObjectLength(obj) //2

9、获取元素相对于浏览器窗口的位置，返回一个{x,y}对象

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 };

}

10、判断某个字母在字符串中出现的次数

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

11、计算出数组中出现次数最多的元素

var arrayObj = [ 1, 1, 2, 3, 3, 3, 4, 5, 5];

var tepm = '',count = 0;

var newarr = new Array();

for( var i= 0;i

if (arrayObj[i] != - 1) {

temp = arrayObj[i];

}

for( var j= 0;j

if (temp == arrayObj[j]) {

count++;

arrayObj[j] = - 1;

}

}

newarr.push(temp + ":" + count);

count = 0;

}

　　 for( var i= 0;i

　　console.log(newarr[i]);

　　}

12、数组filter（搜索功能）

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']

13、copy 对象（第一种）

//第一种

var cloneObj = function(obj) {

var newObj = {};

if (obj instanceof Array) {

newObj = [];

}

for ( var key in 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 prop in origin){

target[prop] = origin[prop];

}

return target;

}

14、深度克隆

var newObj ={};

function deepClone(origin,target){

var target = target || {},

toStr = Object.prototype.toString,

arrStr = "[object Array]";

for( var prop in 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)

15、求数组最大值和最小值

Array.prototype.max = function(){

return Math.max.apply({}, this)

}

Array.prototype.min = function(){

return Math.min.apply({}, this)

}

console.log([ 1, 5, 2].max())

16、json数组去重

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;

}

17、对比两个数组，取出交集

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"]))

18、数组和对象比较。取出对象的key和数组元素相同的

var arr = ['F00006','F00007','F00008'];

var obj = {'F00006':[{'id':21}],'F00007':[{'id':11}]}

var newobj = {};

for( var item in obj){

if(arr.includes(item)){

newobj[item] = obj[item]

}

}

console.log(newObj)

19、删除数组中某个元素

//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

}

20、判断数组是否包含某个元素

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

后续再继续增加~~