Last Updated: September 09, 2019
·
1.265K
· bogdancernat

Use this for variables that you need to represent a toggle state

I was working with some events in JavaScript and needed to toggle the state of some canvas objects when pressing a button. I usually see colleagues of mine writing something like:

var toggle = 0;
var chmodButton = document.querySelector("#chmod");
chmodButton.addEventListener("click",function(){
    if(toggle == 0){
        toggle = 1;
    }
    else{
        toggle = 0;
    }
});

which is totally fine. It works. But why not change the function that is called when the event happens into something like this:

chmodButton.addEventListener("click",function(){
    toggle = (toggle+1)%2;
)};

It skips the if(...) part and you have a nice one line of code that changes the variable from 0 to 1 to 0 and so on...

Another way to do it (thanks to @piatra for the suggestion) is to use var toggle = true instead of var toggle = 0 and change the code inside the event function to :

chmodButton.addEventListener("click",function(){
    toggle = !toggle;
)};

Also as a side note, this isn't specifically for JavaScript, I just wrote it here like this :)

5 Responses
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toggle = !toggle;

over 1 year ago ·

@piatra Sure, this is a nice way to do it too :D

over 1 year ago ·

Also, toggle = 1 - toggle;

over 1 year ago ·

@twolfson Ha! nice! didn't think of this.

over 1 year ago ·

...and toggle = toggle ^ 1 (xor 1) which can be rewritten as

toggle ^= 1;
over 1 year ago ·