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Other References

CSSStyleDeclaration JS Conversion

Window setInterval()


Display "Hello" every second (1000 milliseconds):

setInterval(function () {element.innerHTML += "Hello"}, 1000);
Try it Yourself »

Call displayHello every second:

setInterval(displayHello, 1000);
Try it Yourself »

More examples below.


The setInterval() method calls a function at specified intervals (in milliseconds).

The setInterval() method continues calling the function until clearInterval() is called, or the window is closed.

1 second = 1000 milliseconds.


To execute the function only once, use the setTimeout() method instead.

To clear an interval, use the id returned from setInterval():

myInterval = setInterval(function, milliseconds);

Then you can to stop the execution by calling clearInterval():


See Also:

The clearInterval() Method

The setTimeout() Method

The clearTimeout() Method


setInterval(function, milliseconds, param1, param2, ...)


Parameter Description
function Required.
The function to execute
milliseconds Required.
The execution interval.
If the value is less than 10, 10 is used
param1, param2, ... Optional.
Additional parameters to pass to the function
Not supported in IE9 and earlier.

Return Value

Type Description
A numberThe id of the timer.
Use this id with clearInterval() to cancel the timer.

More Examples


Display the time like a digital watch:

setInterval(myTimer, 1000);

function myTimer() {
  const date = new Date();
document.getElementById("demo").innerHTML = date.toLocaleTimeString();
Try it Yourself »


Using clearInterval() to stop the digital watch:

const myInterval = setInterval(myTimer, 1000);

function myTimer() {
  const date = new Date();
  document.getElementById("demo").innerHTML = date.toLocaleTimeString();

function myStopFunction() {
Try it Yourself »


Using setInterval() and clearInterval() to create a dynamic progress bar:

function move() {
  const element = document.getElementById("myBar");
  let width = 0;
  let id = setInterval(frame, 10);
  function frame() {
    if (width == 100) {
    } else {
      element.style.width = width + '%';
Try it Yourself »


Toggle between two background colors once every 500 milliseconds:

const myInterval = setInterval(setColor, 500);

function setColor() {
  let x = document.body;
  x.style.backgroundColor = x.style.backgroundColor == "yellow" ? "pink" : "yellow";

function stopColor() {
Try it Yourself »


Pass parameters to the function (does not work in IE9 and earlier):

setInterval(myFunc, 2000, "param1", "param2");
Try it Yourself »

However, if you use an anonymous function it works in all browsers:

setInterval(function() {myFunc("param1", "param2")}, 2000);
Try it Yourself »

Browser Support

setInterval() is supported in all browsers:

Chrome Edge Firefox Safari Opera IE
Yes Yes Yes Yes Yes Yes