In today’s post, I would like to touch on another JavaScript timing function…setInterval(). You use setInterval to call a function/run some code over and over for a specified period of time. Let’s look at an example…
[code lang=”js”]
// Create a function to call and run the code over and over
function someFunction() {
// Function runs the setInterval method. This will run the alert code
// over and over every 3 seconds
setInterval(function(){
alert("setInterval is running!");
}, 3000); // 3000 milliseconds = 3 seconds
}
[/code]
You can also pass a function to the setInterval() rather than have the functionality within the method itself…
[code lang=”js”]
// Create a variable to hold the setInterval call var someVar;
function someFunction() {
// Call setInterval method to run myFunc every 3 seconds
someVar = setInterval(myFunc, 3000);
}
// myFunc to run alert
function myFunc() {
alert("setInterval is running!");
}
[/code]
This code does pretty much the same as the previous example, but what is nice about this is you can separate and encapsulate your code to make modification and maintenance easier.
Now, a question you might be asking is, “How do I stop it from running every three seconds?” JavaScript has a method for that…clearInterval(). Just call clear interval and pass the variable that is housing the setInterval call and it will stop. SO if I wish to stop the previous example, the code would be as follows…
[code lang=”js”]
// Stop the 3 second alert
clearInterval(someVar);
[/code]
Side note: If you wish to run a function through setInterval that requires parameters, you simply pass the parameters through the setInterval call…
[code lang=”js”]
// Example setInterval passing 2 parameters
setInterval(myFunc, 3000, param1, param2)
[/code]
Timing functionality is very helpful in certain situations. This one combined with the setTimeout() method, can allow you to have some automation within your program.
Happy Coding!
Clay Hess
