1.复制数组
var arr=[1,2,3];
//var arr2=Array.from(arr);
var arr2=[...arr];
arr.pop();
console.log(arr); //[1,2]
console.log(arr2); //[1,2,3]
2.将arguments转换为数组
function test(...args){
args.push(4);
console.log(args);
}
test(1,2,3); //[1,2,3,4]