clone数组的5种方式

数组对象在JavaScript中默认是引用类型。顾名思义、它是引用实际值，而自身不是实际值。由于这个原因，使用赋值操作（=）拷贝数组只是拷贝原始值的引用而不是实际的值。
在本文中，我们将介绍用JavaScript实际复制数组的5种方法。

1、扩展运算符

let clubs = ['Chelsea', 'Liverpool', 'Mancity', 'Real Madrid']
console.log(clubs)

//Create a clone Es6 way
let clonedClubs = [...clubs]
console.log(clonedClubs)

2、for() 循环

let clubs = ['Chelsea', 'Liverpool', 'Mancity', 'Real Madrid']
clonedClubs = [];
for (i = 0; i < clubs.length; i++) {
  clonedClubs[i] = clubs[i];
}
console.log(clonedClubs)

3、Array map()

let clubs = ['Chelsea', 'Liverpool', 'Mancity', 'Real Madrid']
cloning = (i) => i;

clonedClubs = clubs.map(cloning)
console.log(clonedClubs)

4、Array filter()

let clubs = ['Chelsea', 'Liverpool', 'Mancity', 'Real Madrid']

clonedClubs = clubs.slice();
console.log(clonedClubs)

4、Array slice()

let clubs = ['Chelsea', 'Liverpool', 'Mancity', 'Real Madrid']

clonedClubs = clubs.slice();
console.log(clonedClubs)