Sometimes, administrators want to perform manipulations that GlideForm cannot do. This might include supporting additional events, such as onmouseover, or altering the layout of the page. Although I'll tell you how you can achieve this, I recommend that you don't use this technique in your production instance!
Client Scripts allow you to run code when a field changes or when the form is loaded or submitted. However, the browser can inform JavaScript code about many more events, such as zooming the view, moving a mouse, or dragging files.
One way is to create an onLoad client script that sets up these events manually. The following code uses some undocumented functions of the ServiceNow platform to run scripts when the mouse moves over the Departure field on the Reservation form. Let's try this out:
Navigate to System Definition > Client Scripts. Then, click...