GlideAjax example to get Data from Server side to Client Side ServiceNow

GlideAjax best example to get data from Server side to client side ServiceNow

Client Script:

function onChange(control, oldValue, newValue, isLoading, isTemplate) {
    if (isLoading || newValue === '') {
        // return;
    }
     if (g_form.isNewRecord() && newValue != undefined && newValue != "") {
          var ga = new GlideAjax('sn_customerservice.getParentData');
        ga.addParam('sysparm_name', 'getData');
        ga.addParam('sysparm_parent', newValue); // When you want to pass a value
        ga.getXMLAnswer(getDataParent);
    }
     function getDataParent(answer) {
         var ans = answer.split(",");
        g_form.setValue("u_customer_name", ans[0]);
        g_form.setValue("u_contract_number", ans[1]);
    }
}

Script Include

var getParentData = Class.create();
getParentData.prototype = Object.extendsObject(global.AbstractAjaxProcessor, {
    getData: function() {
        var obj = '';
        var gr = new GlideRecord("sn_customerservice_flex_financial_case");
        if (gr.get(this.getParameter('sysparm_parent'))) {
             obj = gr.u_customer_name.getDisplayValue() + "," + gr.u_contract_number.getDisplayValue();
          }
         return obj;
    },
    type: 'getParentData'
});