Getting employee ID to fill in a read only box

[Eli Hurst]

Overview:
I want to grab the element string of 'user_name' from the table "sys_user" based on what user is populated in the "Request For" field of a request template. Then take the 'user_name' element and put it in a read only field farther down the request form. I was trying to get it to happen onChange. This is the code I have so far, and I am not sure what I am doing wrong here. The 2 pieces of code below are the script include as well as the client script. The console.log() and the alert() were just for my testing purposes. Any assisstance would be helpful. Thank you.

Script Include:

var GetEmployeeID = Class.create();
GetEmployeeID.prototype = Object.extendsObject(AbstractAjaxProcessor, {
    getUserEmpID: function() {

        var _userSysid = this.getParameter('sysparm_user_name');
        var emp = "";
        var user = new GlideRecord('sys_user');
        user.addQuery('user_name', _userSysid);
        user.query();
        if (user.next()) {
            emp = user.getElement('user_name');

        }
        return emp;
    },
    type: 'GetEmployeeID'
});

Client Script

function onChange (control, oldValue, isLoading, newValue, isTemplate) {
	if (isLoading) {
		return;
	}
	var ga = new GlideAjax('GetEmployeeID');
	ga.addParam('sysparm_name', 'getUserEmpID');
	ga.addParam('sysparm_user_name', newValue);
	ga.getXML(setUserValue);
	function setUserValue(response)
	{
		var ans = response.responseXML.documentElement.getAttribute("answer");
		console.log(ans);
		alert(ans);
	}
}

[Hitoshi Ozawa]

Dot walked variable are retrieved synchronously, that's where the error message is coming from.

To test, try adding a new variable on the form that's a reference field to sys_user and assign the onChange to that new variable. The script should work.

[Eli Hurst]

I added 4 images of the variable field type, its specifications, and the updated client script settings per your instructions. I also noticed a pop up message (3rd image) in my script include section, and kinda thought that could be causing the issue?

[Hitoshi Ozawa]

Just to confirm. Is the variable for onChange now set to "request_for"? 

Is the variable "request_for" a reference to "sys_user" table?

[Hitoshi Ozawa]

The message can be ignored. ServiceNow used to allow developers to manipulate DOM from Client Script. They decided to disallow that by default because it ServiceNow may change the DOM structure in the new version. To keep compatibility, developers can override the default by unchecking "Isolate script". Unless doing DOM manipulation, it's better to keep it checked.

[Eli Hurst]

HAlso here is the Script Include options I have selected