The setInterval() method in JavaScript can be used to perform periodic (in milliseconds) evaluation of expressions or call a JavaScript function.
The setInterval() method continues calling the function until clearInterval()
is called, or the window is closed.
1 second = 1000 milliseconds.
setInterval(function, milliseconds, param1, param2, ...)
Parameters: This function accepts the following parameters:
- function: This parameter holds the function name which is to be called periodically.
- milliseconds: This parameter holds the period, in milliseconds, setInterval() calls/executes the function above.
- param1, param2, …: Some additional parameters to be passed as input parameters to function.
Return Value: The id of the timer. Use this id with clearInterval() to cancel the timer.
<!DOCTYPE html>
<html>
<head>
<title>
How to call a function
repeatedly every 5
seconds in JavaScript ?
</title>
</head>
<body>
<p>
Click the button to start
timer, you will be alerted
every 5 seconds until you
close the window or press
the button to stop timer
</p>
<button onclick="startTimer()">
Start Timer
</button>
<button onclick="stopTimer()">
Stop Timer
</button>
<script>
var timer;
function startTimer() {
timer = setInterval(function() {
alert("5 seconds are up");
}, 5000);
}
function stopTimer() {
alert("Timer stopped");
clearInterval(timer);
}
</script>
</body>
</html>