Remove null values from array using Array.indexOf?

Question

I'm trying to find if there's a null value in my array without using for loops, mainly something similar to Array.indexOf. Undefined is NOT a string, it's a null value that comes up as undefined when I use console.log(ARRPREFIX)

var arr = ["**", undefined, null];
if (arr.indexOf(null) > -1) {
  console.log("Should be null");
  arr.splice(arr.indexOf(null), 1);
}

Above is my code, however it doesn't detect the undefined value, I also tried putting in "undefined" instead but that doesn't work.

You dont have an "undefined value", you have a string which so happens to have the characters undefined. It's as far from undefined as undefined can be — Jamiec
– Jamiec, Commented Jul 10, 2017 at 11:22
undefined is not the actual string undefined, it's a null value that comes up as undefined when I use console.log(ARRPREFIX) to print the array. — Mad_ Questionnaire
– Mad_ Questionnaire, Commented Jul 10, 2017 at 11:29
Just use arr.filter(Boolean) It should remove falsy values — abhishekkannojia
– abhishekkannojia, Commented Jul 10, 2017 at 11:32

Alberto Trindade Tavares · Accepted Answer · 2017-07-10 11:37:42Z

8

You can use filter to filter out falsy values (null, undefined, etc):

var array = [2, 3, null, 4, undefined, 5];
array = array.filter(Boolean);

console.log(array);

edited Jul 10, 2017 at 11:37

answered Jul 10, 2017 at 11:20

Alberto Trindade Tavares

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10 Comments

abhishekkannojia Over a year ago

what about undefined ?

Alberto Trindade Tavares Over a year ago

See my edited answer. Just fixed to handle undefined also

Jamiec Over a year ago

And did you notice the undefined is not actually undefined

Alberto Trindade Tavares Over a year ago

I considered undefined, and not "undefined". If you want to filter out the string "undefined", it is just a matter of adjusting the filter

abhishekkannojia Over a year ago

You can shorten it removing inner function to filter: array.filter(Boolean)

|

azurinko · Accepted Answer · 2017-07-10 11:20:57Z

-2

I think those javascript array functions use loops on background anyway.

answered Jul 10, 2017 at 11:20

azurinko

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2 Comments

Mad_ Questionnaire Over a year ago

The point is I don't want to loop through my entire array and delete null/undefined values, since overtime it will get bigger so for loops just won't do.

azurinko Over a year ago

Those functions are going to be executed anyway, how do you thing array functions work? You can't get value of it without looping trought array. Index of is going to do that anyway...

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