Home>Article>Web Front-end> How to use Spread operator (...) in JavaScript? 8 methods introduced

How to use Spread operator (...) in JavaScript? 8 methods introduced

青灯夜游
青灯夜游 forward
2020-06-29 10:40:38 2526browse

How to use Spread operator (...) in JavaScript? 8 methods introduced

The spread operator (...) was introduced in ES6.

The spread operator expands an iterable object, which is any object that can be looped using aforloop, into its individual elements.

Iterable examples: Array, String, Map, Set, DOM nodes.

1. Use the spread operation operator in log

You can iterate inconsole.logThe object uses the spread operation operator

How to use Spread operator (...) in JavaScript? 8 methods introduced

2. Use the spread operation operator to copy the array

How to use Spread operator (...) in JavaScript? 8 methods introduced

Copy object

let user = {name : "John", age : 20 } let userCopy = {...user}
The stretch operation operator does not perform a deep copy.

3. Extended operation operator merge

How to use Spread operator (...) in JavaScript? 8 methods introduced

Merge objects

Merge objects , if a key already exists, it is replaced with the last object with the same key.

let user1 = {name : "John", age : 20 }; let user2 = {name : "Ram", salary: '20K' }; let userCopy = {...user1, ...user2}; userCopy ; // {name : "Ram", age :20 , salary : '20K'};

4. The spread operation operator is passed as a parameter

function sum(a, b) { return a+b; } let num = [1,2]; sum(...num); // 3

andmathFunctions are used together

let num = [5,9,3,5,7]; Math.min(...num); Math.max(...num);

5. The extension operator is used in destructuring variables

How to use Spread operator (...) in JavaScript? 8 methods introduced

Destructuring the object

let user = {name : "Ram", age: 20, salary: '20K', job : "Tester" }; let { name, age, ...details } = user; name; // Ram age; // 20 details; // {salary: '20K', job : 'Tester'};

6. Convert the NodeList object to an array

NodeList Similar to an array, but without all the methods ofArray, such asforEach,map,filter, etc.

let nodeList = document.querySelectorAll('.class') var nodeArray = [...nodeList]

7. Convert strings to characters

Strings are also iterable objects, so we can also use. ..to string.

let name = "Ram"; let chars = [...name]; // ["R", "a", "m"]

8. Remove duplicates from an array

let num = [1, 3, 1, 3, 3, 1]; let uniqueNum = [...new Set(num)]; uniqueNum; //[ 1, 3 ]

Original address: https://medium.com/javascript- in-plain-english/8-ways-to-use-spread-operator-in-javascript-b66fcf016efe

Author: Javascript Jeep

Reprinted from: https://segmentfault.com/ a/1190000023023909

Recommended related tutorials:JavaScript video tutorial

The above is the detailed content of How to use Spread operator (...) in JavaScript? 8 methods introduced. For more information, please follow other related articles on the PHP Chinese website!

Statement:
This article is reproduced at:segmentfault.com. If there is any infringement, please contact admin@php.cn delete