JavaScript® Bible, Sixth Edition

Chapter 24. Select, Option, and FileUpload Objects

IN THIS CHAPTER

• Triggering action based on a user's selection in a pop-up or select list

• Modifying the contents of select objects

• Using the fileUpload object

Selection lists—whether in the form of pop-up menus or scrolling lists—are space-saving form elements in HTML pages. They enable designers to present a lot of information in a comparatively small space. At the same time, users are familiar with the interface elements from working in their own operating systems' preference dialog boxes and application windows.

However, selection lists are more difficult to script, especially in older browsers, because the objects themselves are complicated entities. Scripts find all the real data associated with the form control in option elements that are nested inside select elements. As you can see throughout this chapter, backward-compatible references necessary to extract information from a select element object and its option objects can get pretty long. On the upside, the most painful backward compatibility efforts are all but unnecessary given the proliferation of modern browsers.

The other object covered in this chapter, the fileUpload input object, is frequently misunderstood as being more powerful than it actually is. It is, alas, not the great file transfer elixir desired by many page authors.

select Element Object

For HTML element properties, methods, and event handlers, see Chapter 15.

Properties	Methods	Event Handlers
†See "Text Input Object" ...