Hi Millie,
There's a couple different ways to get the value of a field. The window of the form holds a copy of the item that gets updated as users fill in data in the fields of the form. Because of this you can get the value of the fields directly from this copy of the item like so. You'd just need to updated the bolded text to match the name of the property you're looking for.
document.thisItem.getProperty("item_number");
Alternatively, you can get the value directly from the HTML element of the field. This is helpful if the form that you're using isn't linked to an item like one opened from a dialog. To get the value of the field directly, you can use the sample code below.
getFieldByName("item_number").getElementsByTagName("input")[0].value
Similarly, you'd just need to update the bolded text to match the name of the field you're looking for.
Chris
Christopher Gillis
Aras Labs Software Engineer