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JavaScript

Posted by Jason Pallone
Jason Pallone
11,340 Points

what does ! do in javascript IF statments?

if(!side){ } what does that ! mean here?

Thanks in advance!

2 Answers

Michael Hulet
Michael Hulet
47,913 Points

You can read it as "not". The unary ! operator inverts a boolean, to true becomes false and false becomes true. for example:

const truth = !false; // truth contains the value true
const falsehood = !true; // falsehood contains the value false

if(truth){
    alert("This alert will be shown");
}

if(falsehood){
    alert("This alert will not be shown");
}
Jason Pallone
Jason Pallone
11,340 Points

Thanks that helps a lot!

Aayush Mitra
Aayush Mitra
24,904 Points
Aayush Mitra
Aayush Mitra
24,904 Points

If you just had:

if(side) {}

That would also mean if(side === true) {} But the ! Means:

if(side === false) {}

Hope this helps!

Thanks :)

Jason Pallone
Jason Pallone
11,340 Points

Awesome, thanks for the help!