详解JavaScript数组开头添加元素的3种方法

今天，我们来一起学习一下如何把元素添加到数组的开头。

1.Array.unshift()

let fruits = ["Apple", "Banana", "Mango"];

fruits.unshift("Orange");
console.log(fruits);
// Prints ["Orange", "Apple", "Banana", "Mango"] 
fruits.unshift("Guava", "Papaya");
console.log(fruits);
// Prints ["Guava", "Papaya", "Orange", "Apple", "Banana", "Mango"]

2.使用展开运算符(...)

var fruits = ["Apple", "Banana", "Mango"];

var moreFruits = ["Orange", ...fruits];
console.log(moreFruits);
// Prints ["Orange", "Apple", "Banana", "Mango"] 
var someoMoreFruits = ["Guava", "Papaya", ...moreFruits];
console.log(someoMoreFruits);
// Prints ["Guava", "Papaya", "Orange", "Apple", "Banana", "Mango"] 
console.log(fruits);
// Prints ["Apple", "Banana", "Mango"]

3.使用 Array.concat()

我们还可以使用concat()方法在开头连接两个(或更多)数组。

var fruits = ["Apple", "Banana", "Mango"];
var moreFruits = ["Orange"];
var someoMoreFruits = ["Guava", "Papaya"];

var allFruits = someoMoreFruits.concat(moreFruits, fruits);
console.log(allFruits);
// Prints ["Guava", "Papaya", "Orange", "Apple", "Banana", "Mango"]

原文地址：https://codingnconcepts.com/javascript/how-to-add-element-at-beggining-of-javascript-array/

作者：Orkhan Jafarov

译文地址：https://segmentfault.com/a/1190000039129785

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