Creating a high-performing JavaScript script using AJAX: Tips and Tricks

When it comes to structuring my JavaScript scripts, I often find myself following a similar pattern when dealing with AJAX or server responses. However, I don't believe this is the most efficient method. Is there a better approach for handling these types of scripts?

function someclass() {

    //define internal variables here
    this.var1 = null;
    this.var2 = null;
    ...

    //AJAX function to retrieve critical information for other functions
    this.getAJAX = function() {
        self = this;
        urls = "someurlhere";
        //using jQuery ajax
        $.ajax({
            type: "GET",
            url: url,
            dataType: 'json',
            complete: function (xhr, textStatus) {
                //parse and process server response
                data = JSON.parse(xhr.responseText);
                self.processAJAX(data);
            }
         })

    this.processAJAX = function(data) {
        //set internal variables based on server response

        //now that variables are set, call other functions
        this.doSomething();
    }

    this.doSomething = function() {
        //perform some action
    }

}

Using the script would look like this:

//create an instance of the class
foo = new someClass();

//fetch server information
foo.getAjax();

The issue lies in the fact that calling `doSomething` immediately may not work as intended due to the delay in server response time.

How can we address this problem?

I'm sure this question has been addressed on platforms like StackOverflow, but I haven't found a satisfactory answer yet. Any guidance or resources you could provide would be greatly appreciated. Thank you.

Answer №1

One common approach is to incorporate a callback function into your asynchronous method within a class, which will be triggered by the class upon completion of the operation.

function MyClass() {
    this.makeAjaxRequest = function(callback) {
        this.callbackAfterAjax = callback;
        ...
    });

    this.handleAjaxResponse = function(data) {
        ...
        if (this.callbackAfterAjax) this.callbackAfterAjax();
    }
}

You can then structure your code using a closure callback similarly to how you would with jQuery's $.ajax:

var instance = new MyClass();
instance.makeAjaxRequest(function() {
    instance.doSomethingOnCompletion();
});

Answer №2

If you're looking to implement an ajax event listener or a callback, it's recommended to conduct some research for potential solutions. While many options may be jQuery-centric, it is feasible to achieve this without relying on jQuery if it's not suitable for your specific application.

For those using jQuery, the pertinent documentation can be found at http://api.jquery.com/jQuery.ajax/. Although it doesn't explicitly refer to it as an event listener, pay attention to the section discussing the `context` and the callback for `success`.

An alternative approach could involve making your ajax calls synchronously instead of asynchronously. (Once again, conducting some in-depth searches should yield ample information.) However, if you opt for this method, it's important to ensure that the synchronous call doesn't cause your app to hang while waiting for a response.

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