What exactly does this do?

Question

So I got this code from somebody not too long ago.

I was looking through it, and noticed that the js contained no click event anywhere.

So I checked the button and found this. No idea what it actually does.

Also
run is a var set to "TRUE"

<button onclick="run =!run">Toggle</button>
https://code.sololearn.com/W3Bt5Niq823X/?ref=app

Answer 1

When we click on the button, it toggles the value of the variable 'run' (if it's true it makes it false and if false it makes it true)

and next,
function Count() {
if(run) document.getElementById("output").innerHTML = ++i;
setTimeout("Count()", 100);

}

if(run) {
//code here
}
If the value of run is true it executes the code and if false , it does nothing

Answer 2

js runs independently so no onclick event required

when button is clicked, "run" is set to false and line no.9 in js is not executed and counter stops

on second click, "run" is set to true and line no. 9 is executed, incrementing the counter