Detailed explanation of 3 ways to add elements at the beginning of JavaScript arrays

This article will introduce you to 3 methods of adding elements to the beginning of an array in JavaScript. It has certain reference value. Friends in need can refer to it. I hope it will be helpful to everyone.

#Today, let’s learn how to add elements to the beginning of an array.

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.Use spread operator(...)

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.Use Array.concat()

We can also use the concat() method to concatenate two (or more) arrays at the beginning.

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"]

Original address: https://codingnconcepts.com/javascript/how-to-add-element-at-beggining-of-javascript-array/

Author: Orkhan Jafarov

Translation address: https://segmentfault.com/a/1190000039129785

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