Check if function is already loaded

Hi,

I’m having some troubles of how to find out that my page has already loaded a javascript function before.

Let me explain the situation, I have a page with some tabs (this page loads some javascript functions when it loads, when you click on one of the tabs a ajax call is performed (with YUI no jQuery :() and loads a another page into the ‘body’ of that tab, when this page is loading I need to find out if a specific javascript function has been loaded before.

Anyone knows how to do this with javascript?

Thanks!

You can use a variable.

var myFunctionLoaded = false;

In your function place this at the bottom:

myFunctionLoaded = true;

<script type="text/javascript">

    function myFunction() {}

    if(typeof myFunction === "undefined") {

        console.log("function does not exist");

    }
    else {

        console.log("function exists");

    }

    /*

    // or

    var functionExists = typeof myFunction !== "undefined";
    console.log(functionExists);

    */

</script>

It doesn’t help. If the function is not loaded, what are you going to do? get mad?

The solution is to make sure that this function code is loaded before the JavaScript code that binds the click event. This will make sure that when a user click, it’ll work properly or not at all.

To improve the UI experience, you can add a loader with CSS and remove it when the all required JavaScript is loaded.

How to load JavaScript? There are lot of ways to do that. It depends on your specific case. There are libraries like RequireJS (http://requirejs.org/) which can help you do the job and don’t need jQuery and there is an easy way: Put the scripts in order.