Filter null from an array in JavaScript

Question

I have a task to remove false, null, 0, "", undefined, and NaN elements from an given array. I worked on a solution which removes all except null. Anyone can expla

Answer 1

You can use Array.prototype.filter for truthy value check - see demo below:

function bouncer(array) {
  return array.filter(function(e) {
    return e;
  });
}

console.log(bouncer([1,"", null, NaN, 2, undefined,4,5,6]));

Answer 2

It is a problem with NaN, because

NaN !== NaN

read more here: Testing against NaN.

For filtering the values, you could check for truthyness.

function bouncer(arr) {
    return arr.filter(Boolean);
}

console.log(bouncer([1, "", null, NaN, 2, undefined, 4, 5, 6]));

Answer 3

Use

function bouncer(arr) {
 return arr.filter(function(item){
   return !!item;
 });
}

console.log(bouncer([1,"", null, NaN, 2, undefined,4,5,6]));

Answer 4

Well, since all of your values are falsy, just do a !! (cast to boolean) check:

[1,"", null, NaN, 2, undefined,4,5,6].filter(x => !!x); //returns [1, 2, 4, 5, 6]

Edit: Apparently the cast isn't needed:

[1,"", null, NaN, 2, undefined,4,5,6].filter(x => x);

And the code above removes null just fine, it's NaN that's the problem. NaN !== NaN as Nina says in her answer.