GlideAjax — A Revisit

I wrote about AJAX back in 2014, but I really like this topic so I thought it was worth revisiting with a fuller example.

Quick Recap: Synchronous vs Asynchronous

Synchronous is a real-time communication method where each party receives messages instantly, and the requestor needs to wait for the request to complete before continuing.

Asynchronous is a communication method where each party processes messages whenever it's possible to do so, rather than doing so immediately upon receipt. The requestor immediately continues with its work without waiting for a result.

When to Use GlideAjax

Use GlideAjax when you want to trigger a server-side function from the client side without reloading the entire form.

A Practical Example

Suppose a Service Desk manager wants customers to see their last opened incident when they try to report an outage. From a technical perspective, you need to:

1. Get the User ID
2. Query the Incident table where the caller equals the User ID
3. Return and display the incident number

The only way to query server-side data from a client script is via a server call — and that means GlideAjax.

Step 1: Script Include

Create a client-callable Script Include that extends AbstractAjaxProcessor:

var AJAXLastINC = Class.create();
AJAXLastINC.prototype = Object.extendsObject(AbstractAjaxProcessor, {
    getLastINC: function() {
        var vl = this.getParameter('sysparm_userid');
        var gr = new GlideRecord('incident');
        gr.addQuery('caller_id.sys_id', vl);
        gr.orderByDesc('opened_at');
        gr.query();
        if (gr.next()) {
            return 'Your last open Incident number ' + gr.number;
        }
    },
    type: 'AJAXLastINC'
});

Step 2: Client Script

Create an onLoad client script to call the Script Include:

function onLoad() {
    var ga = new GlideAjax('AJAXLastINC');
    ga.addParam('sysparm_name', 'getLastINC');
    ga.addParam('sysparm_userid', g_user.userID);
    ga.getXML(GetUserINC);
}

function GetUserINC(response) {
    var answer = response.responseXML.documentElement.getAttribute('answer');
    alert(answer);
}

The key points here: sysparm_name tells the server which method to call, and getXML is asynchronous — the form won't hang waiting for a response.

Summary

| Concept | Detail | |---|---| | Script Include type | Client-callable, extends AbstractAjaxProcessor | | Parameter passing | addParam('sysparm_name', 'methodName') | | Execution | getXML(callbackFunction) — always async | | Response reading | getAttribute('answer') on responseXML |