Creating client-side dynamic dependent list boxes

Client-side dynamic dependent list boxes allow a "child" list box to refresh when a selection is made in a "parent" list box, without having to return to the server. Most dynamic dependent list box models return to the server to requery the dependent list box's recordset. The model described in this TechNote passes dependent list box data to the browser in an array. It uses JavaScript to extract the appropriate values from the array and refresh the "child" list box in the client's browser.

The advantage to this approach is immediate page response; the user does not have to wait for the new page to be delivered from the remote server. The disadvantage is all the data for the dynamic dependent list box is sent to the client as text, thus increasing the size of the requested page. An evaluation must be made whether the increased page size warrants saving return trips to the server. If the amount of data required for the dynamic dependent list box is not significant, page size remains relatively small.