前言
数组去重是很常见的，这里总结一下，本人学过的数组去重的办法
1、数组遍历联合indexOf
indexOf 办法可返回指定元素在数组中首次呈现的地位,如果没有，就返回-1
<script> var obj1 = { name: 'tom', age: 18 }; var obj2 = { name: 'tom', age: 18 }; console.log(obj1 == obj2);// false //这里对象的比拟是比拟对象的援用地址是否雷同 var array = [1, 2, 3, null, 'aa', 'bb', 'aa', 2, 3, { name: 'tom', age: 18 }, { name: 'cat', age: 19 }, { name: 'tom', age: 18 }, undefined, undefined, null] function unique1(arr) { console.time("unique1");// 开始计时，测试程序运行工夫 let list = [] for (var i = 0; i < arr.length; i++) { if (list.indexOf(arr[i]) === -1) { list.push(arr[i]) } } console.timeEnd("unique1");// 完结计时，输入工夫 return list; } console.log(unique1(array));</script>2、Set
Set 属于ES6提供的新的数据结构
<script> //1、Set function unique2(arr) { console.time("unique2"); let list = Array.from(new Set(arr)); console.timeEnd("unique2"); return list; } console.log(unique2(array));</script>3、includes
includes 能够用来判断数组中是否蕴含某个元素
<script> function unique3(arr) { console.time("unique3"); let list = [] for (let i = 0; i < arr.length; i++) { if (!list.includes(arr[i])) { list.push(arr[i]) } } console.timeEnd("unique3"); return list } console.log(unique3(array)); </script>4、reduce联合indexOf
reduce 作为数组办法，能够用来数组遍历
<script> function unique5(arr) { console.time("unique5"); let newArr = Array.from(arr).reduce((pre, now) => pre.includes(now) ? pre : [...pre, now], []) console.timeEnd("unique5"); return newArr } console.log(unique5(map1));</script>5、hasOwnProperty
hasOwnProperty 能够判断是否存在对象属性
<script> function unique5(arr) { console.time("unique5"); var obj = {}; var newArr = arr.filter(function (item, index, arr) { return obj.hasOwnProperty(typeof item + item) ? false : (obj[typeof item + item] = true) }) console.timeEnd("unique5"); return newArr } //后果中，雷同属性值的对象被去重了，阐明hasOwnProperty 在比拟时，是判断每个元素的值是否雷同 console.log(unique5(map));</script>6、总结
残缺代码
<script> var obj1 = { name: 'tom', age: 18 }; var obj2 = { name: 'tom', age: 18 }; console.log(obj1 == obj2); // false //这里对象的比拟是比拟对象的援用地址是否雷同 var array = [1, 2, 3, null, 'aa', 'bb', 'aa', 2, 3, { name: 'tom', age: 18 }, { name: 'cat', age: 19 }, { name: 'tom', age: 18 }, undefined, undefined, null] //1、indexOf function unique1(arr) { console.time("unique1"); // 开始计时，测试程序运行工夫 let list = [] for (var i = 0; i < arr.length; i++) { if (list.indexOf(arr[i]) === -1) { list.push(arr[i]) } } console.timeEnd("unique1"); // 完结计时，输入工夫 return list; } var map1 = [1, 2, 3, 4, 4, 'dog', 'cat', 'dog', undefined, null, undefined, null] console.log(unique1(array)); //2、Set function unique2(arr) { console.time("unique2"); let list = Array.from(new Set(arr)); console.timeEnd("unique2"); return list; } console.log(unique2(array)); //3、includes function unique3(arr) { console.time("unique3"); let list = [] for (let i = 0; i < arr.length; i++) { if (!list.includes(arr[i])) { list.push(arr[i]) } } console.timeEnd("unique3"); return list } console.log(unique3(array)); //4、reduce+indexOf function unique4(arr) { console.time("unique4"); let newArr = Array.from(arr).reduce((pre, now) => pre.includes(now) ? pre : [...pre, now], []) console.timeEnd("unique4"); return newArr } console.log(unique4(array)); //5、hasOwnProperty function unique5(arr) { console.time("unique5"); var obj = {}; var newArr = arr.filter(function (item, index, arr) { return obj.hasOwnProperty(typeof item + item) ? false : (obj[typeof item + item] = true) }) console.timeEnd("unique5"); return newArr } console.log(unique5(array));</script>从下面几个办法的测试能够看出程序运行工夫大小排序（因为数据太小，运行工夫也小）：
hasOwnProperty > reduce + indexOf > includes > indexOf > Set