GlideAjax: How to Call Server-Side Code from Client Scripts

When to use GlideAjax

Use GlideAjax when a Client Script needs data that is only available on the server — like querying a related table, checking a user's group membership, or fetching a value from a reference field that isn't on the current form.

Do not use GlideAjax for simple display logic that can be done client-side with data already on the form.

Step 1: Create the server-side Script Include

The Script Include must be client callable and extend AbstractAjaxProcessor:

var GetUserGroups = Class.create();
GetUserGroups.prototype = Object.extendsObject(AbstractAjaxProcessor, {
    getGroups: function() {
        var userId = this.getParameter('sysparm_user_id');
        var groups = [];
        var gr = new GlideRecord('sys_user_grmember');
        gr.addQuery('user', userId);
        gr.query();
        while (gr.next()) {
            groups.push(gr.group.getDisplayValue());
        }
        return JSON.stringify(groups);
    },
    type: 'GetUserGroups'
});

Step 2: Write the Client Script

function onChange(control, oldValue, newValue, isLoading) {
    if (isLoading || newValue === '') return;
    
    var ga = new GlideAjax('GetUserGroups');
    ga.addParam('sysparm_name', 'getGroups');
    ga.addParam('sysparm_user_id', newValue);
    ga.getXMLAnswer(function(response) {
        var groups = JSON.parse(response);
        console.log('User groups: ' + groups.join(', '));
    });
}

Synchronous vs asynchronous calls

Use getXMLAnswer(callback) for asynchronous calls — always prefer this. The callback receives the return value from your Script Include method as a string.

Avoid getXML() and synchronous patterns — they block the browser UI and are deprecated.

Passing multiple parameters

ga.addParam('sysparm_name', 'myMethod');
ga.addParam('sysparm_param1', value1);
ga.addParam('sysparm_param2', value2);

On the server side, retrieve with this.getParameter('sysparm_param1').

Returning complex data

Return values must be strings. Use JSON.stringify() for complex objects and JSON.parse() in the callback to deserialise:

// Server: return JSON.stringify({count: 5, items: [...]});
// Client: var data = JSON.parse(response);

Error handling

Always validate parameters on the server before using them. If a parameter is missing or invalid, return a JSON object with an error field rather than throwing an exception, which gives the client a way to handle it gracefully.