This article is documenting how we can achieve the following:

• Validate input in a client script asynchronously.
• Prevent the form submit until the input is valid.
• Submit the form when the input has been validated.

How did it use to work?

In a nutshell, many platform Ajax requests used getXMLWait().
getXMLWait() would make a synchronous request to the server and cause script execution to wait until the server responded.

Using ajax in an onSubmit script was as easy as:

1. Executing the request
2. Validating the response
3. Returning true or false

Validate before onSubmit in Mobile/Service Portal

Since all framework Ajax requests are asynchronous you will need to use a callback like in this onSubmit script:

function onSubmit() {
    if (g_scratchpad.isFormValid)
        return true;
    var actionName = g_form.getActionName();
    doAsyncTask(function() {
        g_scratchpad.isFormValid = true;
        g_form.submit(actionName);
    });
    return false;
}