(一个关于filter的问题)实现一个摧毁(destroyer)函数，第一个参数是待摧毁的数组，其余的参数是待摧毁的值

Altcademy Team wrote on 7 February 2018

问题是：实现一个摧毁(destroyer)函数，第一个参数是待摧毁的数组，其余的参数是待摧毁的值。

一开始是这样的：

function destroyer(arr) {
  for(var i=1;i<arguments.length;i++){
     arr=arr.filter(function(x){return x!==arguments[i];});
  }
  return arr;
}
destroyer([1, 2, 3, 1, 2, 3], 2, 3); //结果返回了原数组

后来声明了一个变量存储argumetns[i]就没问题了，Why?

function destroyer(arr) {
  for(var i=1;i<arguments.length;i++){
    var number=arguments[i];
    arr=arr.filter(function(x){return x!==number;});
  }
  return arr;
}

destroyer([1, 2, 3, 1, 2, 3], 2, 3);

Hi @GreatAuk, you can have a look at the following repl https://repl.it/Cn6r

What is happening is the first arguments is the arguments of the destroyer function, the second arguments is the arguments of the filter callback function.

function destroyer(arr) {
  for(var i=1;i<arguments.length;i++){
    console.log('arguments1', arguments)
    // => arguments1 { '0': [ 1, 2, 3, 1, 2, 3 ], '1': 2, '2': 3 }

    arr = arr.filter(function(x){
      console.log('arguments2', arguments);
      // => argument2 { '0': 1, '1': 0, '2': [ 1, 2, 3, 1, 2, 3 ] }
      return x!==arguments[i];
    });
  }
  return arr;
}

destroyer([1, 2, 3, 1, 2, 3], 2, 3); //结果返回了原数组

But you actually want to compare x with the elements of arr so you have to assign it for each step of the for loop.

for(var i=1;i<arguments.length;i++){
  var number = arguments[i];
  // assign argument element to number so it can be used in the filter callback function
  arr = arr.filter(function(x){return x!==number;});
}