How to toggle a boolean?

问题

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;

回答1:

bool = !bool;

This holds true in most languages.

回答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).

回答3:

bool = bool != true;

One of the cases.

回答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.

回答5:

bool === tool ? bool : tool

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

回答6:

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)

来源：https://stackoverflow.com/questions/11604409/how-to-toggle-a-boolean