设置未知参数
function foo(param1, param2, ...params) {
console.log(param1);
console.log(param2);...console.log(params);
}
foo("a", "b", 1, 2, 3); //a b [1,2,3]
foo("a", "b"); //a b []
数组解构
let...arr = [1, 2, 3];
console.log(...arr); //1 2 3
字符串解构
let str = "abcde";
console.log(...str); // a