How to get opposite boolean value of variable in Javascript

Question

var a = true;

How to get opposite value of a (false) and vice versa?

richardaday · Accepted Answer · 2012-10-07 20:15:19Z

72

>>> a = true;
true
>>> !a;
false

answered Oct 7, 2012 at 20:15

richardaday

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1 Comment

xinthose Over a year ago

This works for a = false as well. I wasn't sure at first.

Cœur · Accepted Answer · 2019-01-30 06:47:48Z

55

Use the logical NOT operator:

!a

edited Jan 30, 2019 at 6:47

Cœur

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answered Oct 7, 2012 at 20:15

zetlen

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3 Comments

Deryck Over a year ago

lol im so sorry if this bumps the post but this answer and its comments couldn't go unrecognized.

SeniorShizzle Over a year ago

@zetlen i laughed hard

watzon Over a year ago

I upvoted because you're right, and you stuck it to their validation!

Ahmed Roshdy · Accepted Answer · 2014-09-18 22:05:04Z

14

This would be much easier

var b = !a

This would make true a false and false a true

answered Sep 18, 2014 at 22:05

Ahmed Roshdy

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Comments

Charlie · Accepted Answer · 2012-10-07 20:24:24Z

4

Something like this, perhaps;

function toggleFlag(value){
   var toggle = value ? false : true;
   return toggle;
}

var a = true;

a = toggleFlag(a);

edited Oct 7, 2012 at 20:24

answered Oct 7, 2012 at 20:17

Charlie

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5 Comments

Justin Niessner Over a year ago

This is entirely too complicated for something this easy.

I Hate Lazy Over a year ago

@JustinNiessner: Considering how basic the question is, I'd be inclined to upvote the most complicated answers provided. But that's just me.

Charlie Over a year ago

Dunno, Justin... The principle is easy to follow, and extensible, no?

zetlen Over a year ago

I like this answer. ! is obscure and unreadable; this is better, more maintainable code.

Charlie Over a year ago

That's how I see it, but !a is far more elegant, tbh.

Thomas Bormans · Accepted Answer · 2016-03-25 14:46:36Z

4

Try the following:

var a = !a;

edited Mar 25, 2016 at 14:46

Thomas Bormans

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answered Mar 25, 2016 at 13:46

Dmitriy Apollonin

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Comments

Alcides Queiroz · Accepted Answer · 2012-10-07 20:17:13Z

3

Use the "not" operator

var a = true;
alert(!a); //=>false

answered Oct 7, 2012 at 20:17

Alcides Queiroz

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Comments

Ratan Uday Kumar · Accepted Answer · 2019-01-08 10:03:55Z

-5

Try like Below

var Boolify = require('node-boolify').Boolify;
var opp_var = !Boolify(myVar);

Refer node-boolify

answered Jan 8, 2019 at 10:03

Ratan Uday Kumar

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1 Comment

Denzel Hooke Over a year ago

Bruh...........

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