Call Script Include in catalog client script.

[Muralikrishna T]

Script Include : 

var PopulateInfo = Class.create();
PopulateInfo.prototype = Object.extendsObject(AbstractAjaxProcessor, {

userInfo: function() {
var usrID = this.getParameter('sysparm_userID');
var gr = new GlideRecord('sys_user');
gr.addQuery('sys_id', usrID);
gr.query();
if (gr.next()) {
var obj = {};
obj.firstname = '' + gr.first_name + '';
obj.lastname = '' + gr.last_name + '';
obj.department = '' + gr.department + '';
obj.location = '' + gr.location + '';
obj.company = '' + gr.company + '';
var json = new JSON();
var data = json.encode(obj);
return data;
}
},
type: 'PopulateInfo'
});

Catalog script :

function onChange(control, oldValue, newValue, isLoading) {
if (isLoading || newValue == '') {
return;
}

//Type appropriate comment here, and begin script below
var ga = new GlideAjax('PopulateInfo');
ga.addParam('sysparm_name','userInfo');
ga.addParam('sysparm_userID', newValue);
ga.getXML(showMessage);
}
function showMessage(response) {
var answer = response.responseXML.documentElement.getAttribute("answer");
//g_form.addInfoMessage(answer);
answer = answer.evalJSON(); //Transform the JSON string to an object
g_form.setValue("first_name", answer.firstname);
g_form.setValue("last_name", answer.lastname);
g_form.setValue("department", answer.department);
g_form.setValue("location", answer.location);
g_form.setValue("company", answer.company);

}