如何在 JS 中的数组开头添加元素

admin

1.Array.unshift()

复制代码
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(...)

复制代码
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()
2 d4 }% P2 h4 u0 x' h. Y/ s  ]9 b$ W: Y       我们还可以使用concat()方法在开头连接两个(或更多)数组。

复制代码
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"]