day1：js数组方法push重写
Array.prototype._push = function (...arg) {
const params = [...arg];
for (let i = 0, len = params.length; i < len; i++) {
this[this.length] = params[i];
}
return this.length;
}
const arr1 = [12];
console.log(arr1._push(11, 1))
console.log(arr1)
