client-scripts

ServiceNow client scripts control browser-based form behavior by implementing onLoad, onChange, onSubmit, and onCellEdit logic. You use the g_form API for field interactions and GlideAjax for asynchronous server-side data exchange to deliver responsive user experiences.

onLoad client scripts execute when a form loads into the browser, useful for initial field setup. onChange client scripts trigger when a user modifies a specific field value, enabling dynamic form validation and dependent field updates as users interact.

GlideAjax enables asynchronous server calls from client scripts to retrieve or validate server-side data without reloading the form. You instantiate the GlideAjax object, specify the server-side script include name, add parameters, and use a callback function to process the response.

g_form API usage requires specific considerations for ServiceNow service portal and mobile contexts. Not all g_form methods are fully supported across mobile and desktop interfaces, so you must verify compatibility and apply mobile-specific patterns to ensure safe, scalable configurations.

Optimizing ServiceNow client script performance involves minimizing server calls, using scratchpad data flows to reduce redundant queries, and applying debugging best practices. You should carefully scope onChange scripts to necessary fields and avoid synchronous GlideAjax calls to maintain form responsiveness.

onSubmit client scripts must return a boolean value to control form submission. If the script returns true, submission proceeds, while returning false stops it. Ensure your validation logic explicitly returns false and uses GlideAjax callbacks correctly to handle asynchronous server-side validation.