I'm new here and need some help with writing a function destroyer() to remove multiple values from an array.

The destroyer() function passes in an array and additional numbers as arguments. The idea is to remove the numbers from the array.

E.g.

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

Output: [1, 1]

destroyer(["tree", "hamburger", 53], "tree", 53) 

Output: ["hamburger"]

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

Output: []

Note: the examples only show 2 additional numbers to remove. But the function destroyer() should be able to remove any number of values (i.e. 4, 5, or 6 parameters).

However, my code does not produce the same result. Specifically, using console.log, I see that my filterer function does not loop properly.

1) Can anyone help me debug?

2) Any better way to write this function?

Thank you very much!!!

function destroyer() {

  var args = Array.prototype.slice.call(arguments); 

  var itemToRemove = args.slice(1);
  console.log(itemToRemove);
  var newArr = args[0];
  console.log(newArr);

  function filterer(value) { 

    for (var i = 0; i < itemToRemove.length; i++) {
      console.log(i);
      console.log(itemToRemove[i]);
      if (value != itemToRemove[i]) {
        return value;
      }
    } 
   }

  return newArr.filter(filterer);
}

I'm new here and need some help with writing a function destroyer() to remove multiple values from an array.

The destroyer() function passes in an array and additional numbers as arguments. The idea is to remove the numbers from the array.

E.g.

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

Output: [1, 1]

destroyer(["tree", "hamburger", 53], "tree", 53) 

Output: ["hamburger"]

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

Output: []

Note: the examples only show 2 additional numbers to remove. But the function destroyer() should be able to remove any number of values (i.e. 4, 5, or 6 parameters).

However, my code does not produce the same result. Specifically, using console.log, I see that my filterer function does not loop properly.

1) Can anyone help me debug?

2) Any better way to write this function?

Thank you very much!!!

function destroyer() {

  var args = Array.prototype.slice.call(arguments); 

  var itemToRemove = args.slice(1);
  console.log(itemToRemove);
  var newArr = args[0];
  console.log(newArr);

  function filterer(value) { 

    for (var i = 0; i < itemToRemove.length; i++) {
      console.log(i);
      console.log(itemToRemove[i]);
      if (value != itemToRemove[i]) {
        return value;
      }
    } 
   }

  return newArr.filter(filterer);
}

• javascript

• If you told us what the criteria was for removing, instead of posting cryptic examples, it would probably be easier to help ? – adeneo Commented Oct 22, 2015 at 6:12
• In the first argument he passes an array, in the further the values he wants to remove – h0ch5tr4355 Commented Oct 22, 2015 at 6:14
• Do you always pass two values for removing? or it can be more? like destroyer([1, 2, 3, 1, 2, 3], 2,4, 3)? – Grundy Commented Oct 22, 2015 at 6:57
• It can be any number of values, e.g. 3 values to remove in your example. – Neong Commented Oct 22, 2015 at 7:02
• I smell freeCodeCamp ;D – Leo Commented Jan 24, 2017 at 18:59

6 Answers 6

Your filterer function can be much simpler:

function filterer (value) {
    return itemToRemove.indexOf(value) === -1;
}

Using Array.prototype.indexOf() can be inefficient pared to object property lookup in terms of time plexity. I would remend looping through the additional arguments once and constructing an object with target elements to be destroyed as keys. Then you can check if a given value is a target or not within a filtering callback that you pass to Array.prototype.filter().

function destroyer() {
    var arr = arguments.length && arguments[0] || [];
    var targets = {};
    for (var i = 1; i < arguments.length; i++) {
        targets[arguments[i]] = true;
    }
    return arr.filter(function (x) {
        return targets[x] === undefined;
    });
}

One downside to this approach is that not all values in JS can be valid properties of an object, since properties must be strings. In this case, you're just using numbers as keys, and those numbers are implicitly converted to strings.

We can pass the arguments an extra parameter to our callback function in our filter() method.

function destroyer(arr) {
  return arr.filter(filterer(arguments)); // Pass arguments
}

function filterer(args) {
  return function(value) { // Actual filter function
    for (var i = 1; i < args.length; i++) {
      if (value === args[i]) // Seek
        return false; // Destroy
    }
    return true; // Otherwise keep
  };
}

This passes all 5 test cases for freeCodeCamp | Basic Algorithm Scripting | Seek and Destroy.

A simple function

function filter(arr, arg1, arg2){

    var j = arr.length;
    while(j){

       if (arr.indexOf(arg1) > -1 || arr.indexOf(arg2) > -1){
          arr.splice(j - 1, 1);
       }
       j--
    }
}

For multiple arguments

A simple function

function filter(){
    var j = -1; 
    for(var i = 1; i < arguments.length; i++){
        j = arguments[0].indexOf(arguments[i]);
        if(j > -1){
           arguments[0].splice(j, 1);
        }
    }
    return arguments[0];
}

you can call this function with no of args eg:

 filter([1,2,3,4,5,6,7,8,9], 1, 3, 5); //return [2,4,6,7,8,9]
 filter([1,2,3,4,5,6,7,8,9], 1); //return [2,3,4,5,6,7,8,9]

There are really good answers here, but you can do it very clean in this way, remember you have an objects option in filter method which you can use in the callback function, in this case i'm using it like : arguments[i] so I can check every value in the arguments array

function destroyer(arr) {

   for(var i = 1; i < arguments.length; i++){
     arr = arr.filter(isIn, arguments[i]);
   } 

   function isIn(element,index, array){
      if (element != this){
         return element;
      }
   }  
   return arr;
}