ajax Getting started with ajax Performing an Asynchronous AJAX Call using TypeScript

Example

Adding a Product to a Shopping Cart

The following example demonstrates how to Add a product (or anything) to a Database Table asynchronously, using AJAX, and TypeScript.

declare var document;
declare var xhr: XMLHttpRequest;

window.onLoad = () =>
{
    Start();
};

function Start()
{
    // Setup XMLHttpRequest (xhr).
    if(XMLHttpRequest)
    {
        xhr = new XMLHttpRequest();
    }
    else
    {
        xhr = new ActiveXObject("Microsoft.XMLHTTP");
    }

    AttachEventListener(document.body, "click", HandleCheckBoxStateChange);
}

function AttachEventListener(element: any, e, f)
{
    // W3C Event Model.
    if(element.addEventListener)
    {
        element.addEventListener(e, f, false);
    }
    else if(element.attachEvent)
    {
        element.attachEvent("on" + e, (function(element, f)
        {
            return function()
            {
                f.call(element, window.event);
            };
        })
        (element, f));
    }

    element = null;
}

function HandleCheckBoxStateChange(e)
{
    var element = e.target || e.srcElement;

    if(element && element.type == "checkbox")
    {
        if(element.checked)
        {
            AddProductToCart(element);
        }
        else
        {
            // It is un-checked.
            // Remove item from cart.
        }
    }
    else
    {
        break;
    }
}

AddProductToCart(e)
{
    var element = <HTMLInputElement>document.getElementById(e.id);

    // Add the product to the Cart (Database table)
    xhr.onreadystatechange = function()
    {
        if(xhr.readyState == 4)
        {
            if(xhr.status == 200)
            {
                if(element != null)
                {
                    console.log("200: OK");
                }
                else
                {
                    console.log(":-(");
                }
            }
            else
            {
                // The server responded with a different response code; handle accordingly.
                // Probably not the most informative output.
                console.log(":-(");
            }
        }
    }

    var parameters = "ProductID=" + encodeURIComponent(e.id) + "&" + "Action=Add&Quantity=" + element.value;

    xhr.open("POST", "../Cart.cshtml");
    xhr.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
    xhr.setRequestHeader("Content-length", parameters.length.toString());
    xhr.setRequestHeader("Connection", "close");

    xhr.send(parameters);

    return e.id;
}

In order to make this example complete, update your server-side code to actually insert this data into the database. The code above assumes you are using C# and have a Cart.cshtml file. However, simply replace cshtml with php, and write your own server-side logic using the language of your choice.