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<arr.length;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 attrin 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<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]);
- }
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 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;
- }
14、深度克隆
- 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)
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 itemin 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