ES6 扩展运算符 – …
1、复制(拷贝)数组(数组元素都是基本数据类型)。
var arr = ['a','b','c'];
var copy = [...arr];
console.log(copy) // ['a','b','c'];
arr === copy //false
2、函数调用(数组作参数)
function add(x, y) {
return x + y;
}
var numbers = [4, 38];
add(...numbers) // 42
3、合并数组
(1) 添加 [ 将B添加到A中](改变了A)
var arr1 = [0, 1, 2];
var arr2 = [3, 4, 5];
es5 ==> Array.prototype.push.apply(arr1, arr2);
es6 ==> arr1.push(...arr2);
arr1 = [0,1,2,3,4,5]
(2) 合并[ 将A 、B 合并到一起](赋给 C )
var arr1 = ['a', 'b'];
var arr2 = ['c'];
var arr3 = ['d', 'e'];
es5 ==> var arr4 = arr1.concat(arr2, arr3);
es6 ==> var arr4 = [...arr1,...arr2,...arr3];
arr1 = ['a', 'b']
arr4 = ["a", "b", "c", "d", "e"]
4、将字符串转为数组
[...'hello']
// [ "h", "e", "l", "l", "o" ]