开发用到的js封装方法（20种）
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 |
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;} |
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;} |
4、动态去重
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var arr = [1,2, 3, 4];function add() {var newarr = [];$('.addEle').click(() => {var rnd = Math.ceil(Math.random() * 10); newarr.push(rnd)for (var i =0; i < newarr.length; i++) { if (arr.indexOf(newarr[i]) == -1) { arr.push(newarr[i]) arr.sort(function (a, b) { return b - a //降序 }); }} console.log(arr)//[1,2,3,4,5,6,7,8,9] })}add() |
5、去除字符串空格(包含三种情况)
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function trim(str) { return str.replace(/^[" "||" "]*/,"").replace(/[" "|" "]*$/,"");// 去除头和尾 return str.replace(/\s/g,'');//去除所有空格 return str.replace(/(\s*$)/g,"");//去除右边所有空格} |
6、判断是否为邮箱地址
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function isEmail(emailStr) { var reg = /^[a-zA-Z0-9]+([._-]*[a-zA-Z0-9]*)*@[a-zA-Z0-9]+.[a-zA-Z0-9{2,5}$]/; var result = reg.test(emailStr); if (result) { alert("ok"); } else { alert("error"); }} |
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'); }} |
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 |
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 };} |
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 |
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]);} |
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'] |
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;} |
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) |
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()) |
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;} |
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"])) |
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) |
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} |
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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