clearInterval() not working

javascript scope setinterval clearinterval

146,621

Solution 1

setInterval returns an ID which you then use to clear the interval.

var intervalId;
on.onclick = function() {
    if (intervalId) {
        clearInterval(intervalId);
    }
    intervalId = setInterval(fontChange, 500);
};

off.onclick = function() {
    clearInterval(intervalId);
};

Solution 2

The setInterval function returns an integer value, which is the id of the "timer instance" that you've created.

It is this integer value that you need to pass to clearInterval

e.g:

var timerID = setInterval(fontChange,500);

and later

clearInterval(timerID);

Solution 3

You're using clearInterval incorrectly.

This is the proper use:

Set the timer with

var_name = setInterval(fontChange, 500);

and then

clearInterval(var_name);

Solution 4

i think you should do:

var myInterval
on.onclick = function() {
    myInterval=setInterval(fontChange, 500);
};

off.onclick = function() {
    clearInterval(myInterval);
};

Solution 5

The setInterval method returns an interval ID that you need to pass to clearInterval in order to clear the interval. You're passing a function, which won't work. Here's an example of a working setInterval/clearInterval

var interval_id = setInterval(myMethod,500);
clearInterval(interval_id);

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146,621

Matt Sanchez

Trying to get proficient using the MEAN stack (Mongo, Express, Angular, Node).

Updated on July 09, 2022

Comments

Matt Sanchez almost 2 years

Possible Duplicate:
JS - How to clear interval after using setInterval()

I have a function that changes the font-family of some text every 500 ms using setInterval (I made it just to practice JavaScript.) The function is called by clicking on an "on" button and the interval is supposed to be cleared using a separate button, "off". However, the "off" button doesn't actually clear the interval, it just continues. I suspect that this has something to do with scope but I'm not sure how to write it any other way. Also, I don't want to do this with jQuery because, after all, I'm doing it to learn.

<body>
<p><span id="go" class="georgia">go</span> Italian</p>
<p>
    <button id="on" type="button" value="turn on">turn on</button>
    <button id="off" type="button" value="turn off">turn off</button>
</p>

<script>
var text = document.getElementById("go");
var on = document.getElementById("on");
var off = document.getElementById("off");

var fontChange = function() {
    switch(text.className) {
        case "georgia":
            text.className = "arial";
            break;
        case "arial":
            text.className = "courierNew";
            break;
        case "courierNew":
            text.className = "georgia";
            break;      
    }
};

on.onclick = function() {
    setInterval(fontChange, 500);
};

off.onclick = function() {
    clearInterval(fontChange);
}; 
</script>
</body>

Matt Sanchez about 11 years

I did look at the MDN spec first but it didn't help me with the problem.
Samiul about 6 years

window.timer = setInterval(fontChange, 500); clearInterval(window.timer)

papo over 7 years

this is fine, but you'll run into another problem if you are using setInterval() (or setTimeout()) in a situation where it's possible to run it multiple time. If you'll click twice, you'll never clear the first setInterval(). You either need if(intervalId !== undefined) { intervalId = setInterval(... or make intervalId an Array if you want more setIntervals on each additional click