Shulou(Shulou.com)05/31 Report--

Today, I would like to share with you the relevant knowledge points of JavaScript commonly used arrays, which are detailed in content and clear in logic. I believe most people still know too much about this knowledge, so share this article for your reference. I hope you can get something after reading this article. Let's take a look at it.

1. Make use of the properties of the object

Use the property that the object property does not have the same name.

Var arr = ["qiang", "ming", "tao", "li", "liang", "you", "qiang", "tao"]; console.time ("nonredundant1"); var nonredundant1 = Object.getOwnPropertyNames (function (seed, item, index) {seed [item] = index; return seed;}, {}); console.timeEnd ("nonredundant1"); console.log (nonredundant1)

The results are as follows:

two。 Using Set data structures

Set is an array-like structure, but there are no duplicate values in the set member. The set () function can take an array or an array of classes to generate a set object. The Array.from method is used to turn two types of objects into real arrays: array-like objects (array-like object and traverable iterable), including ES6's new data structures Set and Map).

Var arr = ["qiang", "ming", "tao", "li", "liang", "you", "qiang", "tao"]; function unique (arr) {return Array.from (new Set (arr))} console.time ("nonredundant2"); var nonredundant2 = unique (arr); console.timeEnd ("nonredundant2"); console.log (nonredundant2)

The results are as follows:

3. Using for loops and splice

Function unique (arr) {for (var I = 0; I)

< arr.length; i++) { for (var j = i + 1; j < arr.length; j++) { if (arr[i] == arr[j]) { //第一个等同于第二个，splice方法删除第二个 arr.splice(j, 1); j--; } } } return arr;}console.time("nonredundant3");var arr = ["qiang", "ming", "tao", "li", "liang", "you", "qiang", "tao"];var nonredundant3 = unique(arr);console.timeEnd("nonredundant3");console.log(nonredundant3); 结果如下： 4.使用indexOf判断去重 function unique(arr) { var array = []; for (var i = 0; i < arr.length; i++) { if (array .indexOf(arr[i]) === -1) { array .push(arr[i]) } } return array;}var arr = ["qiang", "ming", "tao", "li", "liang", "you", "qiang", "tao"];console.time("nonredundant4");var nonredundant4 = unique(arr);console.timeEnd("nonredundant4");console.log(nonredundant4); 结果如下： 5.使用sort排序去重 function unique(arr) { arr = arr.sort() var arrry = [arr[0]]; for (var i = 1; i < arr.length; i++) { if (arr[i] !== arr[i - 1]) { arrry.push(arr[i]); } } return arrry;} var arr = ["qiang", "ming", "tao", "li", "liang", "you", "qiang", "tao"];console.time("nonredundant5");var nonredundant5 = unique(arr);console.timeEnd("nonredundant5"); 结果如下： 6.使用filter function unique(arr) { var obj = {}; return arr.filter(function(item, index, arr){ return obj.hasOwnProperty(typeof item + item) ? false : (obj[typeof item + item] = true) })}var arr = ["qiang", "ming", "tao", "li", "liang", "you", "qiang", "tao"];console.time("nonredundant6");var nonredundant6 = unique(arr);console.timeEnd("nonredundant6");console.log(nonredundant6); 结果如下： 7.使用Map数据结构去重 function unique(arr) { let map = new Map(); let array = new Array(); // 数组用于返回结果 for (let i = 0; i < arr.length; i++) { if (map.has(arr[i])) { // 如果有该key值 map.set(arr[i], true); } else { map.set(arr[i], false); // 如果没有该key值 array.push(arr[i]); } } return array;} var arr = ["qiang", "ming", "tao", "li", "liang", "you", "qiang", "tao"];console.time("nonredundant7");var nonredundant7 = unique(arr);console.timeEnd("nonredundant7");console.log(nonredundant7); 结果如下： 8.使用reduce和include去重 function unique(arr){ return arr.reduce((prev,cur) =>

Prev.includes (cur)? Prev: [... prev,cur], []);} var arr = ["qiang", "ming", "tao", "li", "liang", "you", "qiang", "tao"]; console.time ("nonredundant8"); var nonredundant8 = unique (arr); console.timeEnd ("nonredundant8"); console.log (nonredundant8)

The results are as follows:

These are all the contents of the article "how to duplicate JavaScript arrays". Thank you for reading! I believe you will gain a lot after reading this article. The editor will update different knowledge for you every day. If you want to learn more knowledge, please pay attention to the industry information channel.

Welcome to subscribe "Shulou Technology Information " to get latest news, interesting things and hot topics in the IT industry, and controls the hottest and latest Internet news, technology news and IT industry trends.