Scripting · 6 min read read
ServiceNow Client Scripts Examples: onLoad, onChange, onSubmit
ServiceNow Client Scripts examples using g_form for onLoad, onChange and onSubmit, plus when to use UI Policies instead.
By the NowPath Institute trainer team ·
onLoad: show a message
Runs when the form loads.
function onLoad() {
if (g_scratchpad.isVip) {
g_form.addInfoMessage('VIP caller — handle with priority.');
}
}onChange: react to a field
Runs when a specific field value changes.
function onChange(control, oldValue, newValue, isLoading) {
if (isLoading || newValue === '') return;
g_form.setMandatory('close_notes', newValue == '6');
}onSubmit: validate before save
Return false to stop the submission.
Client Script or UI Policy?
Use UI Policies for simple mandatory, read-only and visibility rules. Use Client Scripts when you need logic, server calls via GlideAjax or messages.