clearInterval doesn't working

Question

var started = false;
function start() {
    var timer;
    if(started === false) {
        timer = setInterval(decrease, 1000);
        started = true;
    } else {
        clearInterval(timer);
        console.log("Should Clear");
    }
}

The setInterval works but when I run the function again, it prints in the console that it should be removed. But it doesn't.

Answer 1

timer is declared inside your function, so when you call it again, it's a new instance.

Try declaring it outside the function, like this:

var started = false;
var timer;
function start() {
    if(started === false) {
        timer = setInterval(decrease, 1000);
        started = true;
    } else {
        clearInterval(timer);
        console.log("Should Clear");
    }
}

Answer 2

timer gets reinitialized every time you call start so the second time you call it, it's not pointing to a timer id to clear.

Answer 3

use like this

var started = false;
var timer;
function start() {

    if(started === false) {
        timer = setInterval(decrease, 1000);
        started = true;
    } else {
        clearInterval(timer);
        console.log("Should Clear");
    }
}

Answer 4

Because timer is in the scope of the function. So when you call it the second time, it is in another scope.