Rumah > Artikel > hujung hadapan web > js实现数组去重的几种方法总结
双层循环,外层循环元素,内层循环时比较值
如果有相同的值则跳过,不相同则push进数组
Array.prototype.distinct = function(){var arr = this, result = [], i, j, len = arr.length;for(i = 0; i < len; i++){for(j = i + 1; j < len; j++){if(arr[i] === arr[j]){ j = ++i; } } result.push(arr[i]); }return result; }var arra = [1,2,3,4,4,1,1,2,1,1,1]; arra.distinct(); //返回[3,4,2,1]
双层循环,外层循环元素,内层循环时比较值
值相同时,则删去这个值
注意点
:删除元素之后,需要将数组的长度也减1.
Array.prototype.distinct = function (){var arr = this, i, j, len = arr.length;for(i = 0; i < len; i++){for(j = i + 1; j < len; j++){if(arr[i] == arr[j]){ arr.splice(j,1); len--; j--; } } }return arr; };var a = [1,2,3,4,5,6,5,3,2,4,56,4,1,2,1,1,1,1,1,1,];var b = a.distinct(); console.log(b.toString()); //1,2,3,4,5,6,56
优点:简单易懂
缺点:占用内存高,速度慢
Array.prototype.distinct = function (){var arr = this, i, obj = {}, result = [], len = arr.length;for(i = 0; i< arr.length; i++){if(!obj[arr[i]]){ //如果能查找到,证明数组元素重复了obj[arr[i]] = 1; result.push(arr[i]); } }return result; };var a = [1,2,3,4,5,6,5,3,2,4,56,4,1,2,1,1,1,1,1,1,];var b = a.distinct(); console.log(b.toString()); //1,2,3,4,5,6,56
运用递归的思想
先排序,然后从最后开始比较,遇到相同,则删除
Array.prototype.distinct = function (){var arr = this, len = arr.length; arr.sort(function(a,b){ //对数组进行排序才能方便比较return a - b; })function loop(index){if(index >= 1){if(arr[index] === arr[index-1]){ arr.splice(index,1); } loop(index - 1); //递归loop函数进行去重 } } loop(len-1);return arr; };var a = [1,2,3,4,5,6,5,3,2,4,56,4,1,2,1,1,1,1,1,1,56,45,56];var b = a.distinct(); console.log(b.toString()); //1,2,3,4,5,6,45,56
indexOf
以及forEach
Array.prototype.distinct = function (){var arr = this, result = [], len = arr.length; arr.forEach(function(v, i ,arr){ //这里利用map,filter方法也可以实现var bool = arr.indexOf(v,i+1); //从传入参数的下一个索引值开始寻找是否存在重复if(bool === -1){ result.push(v); } })return result; };var a = [1,1,1,1,1,1,1,1,1,2,2,2,2,2,2,3,3,3,3,3,3,3,2,3,3,2,2,1,23,1,23,2,3,2,3,2,3];var b = a.distinct(); console.log(b.toString()); //1,23,2,3
Set数据结构,它类似于数组,其成员的值都是唯一的。
利用Array.from将Set结构转换成数组
function dedupe(array){return Array.from(new Set(array)); } dedupe([1,1,2,3]) //[1,2,3]
拓展运算符(...)内部使用for...of循环
let arr = [1,2,3,3]; let resultarr = [...new Set(arr)]; console.log(resultarr); //[1,2,3]
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