输入[1, 2, 3, 4], 10 输出[1, 2, 3, 4, 10]
//错误
function append(arr, item) {
var newArr = arr;
newArr.push(item);
return newArr;
}
//错误
function append(arr, item) {
var newArr = arr.slice(0);
return newArr.push(item);
}
//正确
function append(arr, item) {
var newArr = arr.slice(0);
newArr.push(item);
return newArr;
}