clearInterval() not working [duplicate]
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>
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);
};
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);
i think you should do:
var myInterval
on.onclick = function() {
myInterval=setInterval(fontChange, 500);
};
off.onclick = function() {
clearInterval(myInterval);
};
You're using clearInterval incorrectly.
This is the proper use:
Set the timer with
var_name = setInterval(fontChange, 500);
and then
clearInterval(var_name);