How to toggle a boolean?

Question

Is there a really easy way to toggle a boolean value in javascript?

So far, the best I've got outside of writing a custom function is the ternary:

bool = bool ? false : true;

Answer 1

bool = !bool;

This holds true in most languages.

Answer 2

If you don't mind the boolean being converted to a number (that is either 0 or 1), you can use the Bitwise XOR Assignment Operator. Like so:

bool ^= true;   //- toggle value.

This is especially good if you use long, descriptive boolean names, EG:

var inDynamicEditMode   = true;     // Value is: true (boolean)
inDynamicEditMode      ^= true;     // Value is: 0 (number)
inDynamicEditMode      ^= true;     // Value is: 1 (number)
inDynamicEditMode      ^= true;     // Value is: 0 (number)

This is easier for me to scan than repeating the variable in each line.

This method works in all (major) browsers (and most programming languages).

Answer 3

bool = bool != true;

One of the cases.

Answer 4

Let's see this in action:

var b = true;

console.log(b); // true

b = !b;
console.log(b); // false

b = !b;
console.log(b); // true

Anyways, there is no shorter way than what you currently have.

Answer 5

I was searching after a toggling method that does the same, except for an inital value of null or undefined, where it should become false.

Here it is:

booly = !(booly != false)

Answer 6

bool === tool ? bool : tool

if you want the value to hold true if tool (another boolean) has the same value

Answer 7

In a case where you may be storing true / false as strings, such as in localStorage where the protocol flipped to multi object storage in 2009 & then flipped back to string only in 2011 - you can use JSON.parse to interpret to boolean on the fly:

this.sidebar = !JSON.parse(this.sidebar);