为什么我的for循环只出现一次？

Question

This is one of freecodecamps challenges it passes the for loop inside the filter passes the first element of the array newArg but doesn't for the second one and so on therefore the challenge doesn't pass can someone explain to me why. Please don't write any full solutions as i just want a little help to move forward.

function destroyer(arr) {
  // Remove all the values
  var newArg = [];
  for (var i=1; i < arguments.length; i++){
         newArg.push(arguments[i]);
       }


 var newArray = arr.filter(function(val){
  for (i = 0; i < newArg.length; i++) {
     return val !== newArg[i];
  } 


 });
 return newArray;



}

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

Answer 1

The filter call:

var newArray = arr.filter(function(val){
  for (i = 0; i < newArg.length; i++) {
     return val !== newArg[i];
  } 
});

is the same as:

var newArray = arr.filter(function(val) {
  return val !== newArg[0];
});

because you are returning from the very first iteration.

Solution:

You'll have to wrap the return statement in an if like this:

var newArray = arr.filter(function(val){
  for (i = 0; i < newArg.length; i++) {
     if(val === newArg[i]) { // don't return if val !== newArg[i]
       return true;          // return only when they're ===
     }
  }
  return false;              // default return (nothing is found in the array)
});

Or use an alternative such as Array.prototype.some like this:

var newArray = arr.filter(function(val){
  return newArg.some(function(arg) { // return true if some item pass the test (false otherwise)
     return arg === val;             // the test
  })
});