詳解JavaScript數組開頭添加元素的3種方法

這篇文章跟大家介紹一下JavaScript中將元素加入到陣列開頭的3種方法。有一定的參考價值，有需要的朋友可以參考一下，希望對大家有幫助。

今天，我們來一起學習如何把元素加入到陣列的開頭。

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.使用展開運算子(...)

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()

#我們也可以使用concat()方法在開頭連接兩個(或更多)陣列。

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"]

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

#作者：Orkhan Jafarov

翻譯地址：https://segmentfault.com/a/1190000039129785

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