clearInterval() stops the movingTab specified by setInterval(), but when startTimer() runs again, the tabInterval value is not 0 and is incrementing. What’s the problem? This issue doesn’t actually cause any serious problems with my functionality, but I’m curious as to why.

var tabInterval = null;

function startTimer() {
    if(tabInterval === null) {
        console.log("first : " + tabInterval);
        tabInterval = setInterval(movingTab, 10000);
        console.log("second : " + tabInterval);
    }
}

function stopTimer() {
    if(tabInterval !== null) {
        console.log("third : " + tabInterval);
        clearInterval(tabInterval);
        tabInterval = null;
        console.log("fourth : " + tabInterval);
    }
}

If I do for(var i = 0; i < 999; i++) clearInterval(i), the time does not increase, but the value of tabInterval = setInterval(movingTab, 10000) is not initialized to 0.

ex)
first run ->
first console : null
second console : 2
third console : 2
fourth console : null

second run ->
first console : null
second console : 11
third console : 11
fourth console : null