How to parse null from "null" string value

Question

var hello = 'null';

How do I remove the quotes so var hello will truly equal null (and not a string)? I'm curious on how to do this without using JSON.parse.

You don't. You test your value, and assign accordingly. A counter-question would be "what do you think you would concretely use this for?" because it's a good bet that what you're trying to do has a better way to do it. — Mike 'Pomax' Kamermans
– Mike 'Pomax' Kamermans, Commented Jun 30, 2018 at 1:28
Type in var hello = null;? Or do something like: var hello = 'null'; var bar = hello === 'null' ? null : hello;? — user2864740
– user2864740, Commented Jun 30, 2018 at 1:29
'null' is a string. It doesn't have any quotes, you can't remove them. How did you get this value? Further, what's wrong with JSON.parse? — Adam Jenkins
– Adam Jenkins, Commented Jun 30, 2018 at 1:29
There is something really wrong with your JSON. The stringify JSON should look something like this '{"someObj":null}' and not '{"someObj":"null"}' — Aman Chhabra
– Aman Chhabra, Commented Jun 30, 2018 at 1:40

tonymke · Accepted Answer · 2018-06-30 01:41:15Z

3

Without JSON.parse, you cannot.

You can evaluate hello and alter its value later on in the code, which is much more real-world scenario.

hello = hello === 'null' ? null : hello

answered Jun 30, 2018 at 1:32

tonymke

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Comments

Eugene Kartoyev · Accepted Answer · 2018-06-30 01:40:01Z

0

Assign null, I've just done this:

var a=1;
console.log(a);
a=null;
console.log(a);
console.log(a===null);

Results:

1
null
true

Though, null in JS is also a value.

answered Jun 30, 2018 at 1:40

Eugene Kartoyev

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Elliott Frisch · Accepted Answer · 2018-06-30 01:46:27Z

0

You could eval or parse it from JSON (but eval is a terrible approach, I only mention it for the sake of this specific example). Like,

var hello = JSON.parse('null');
console.log(hello === null);

answered Jun 30, 2018 at 1:30

Elliott Frisch

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eval for this is a sure-fire way to a disaster later on. Your answer should list the caveats of such an approach, if you're suggesting it.