USING EVENT LISTENERS WITH THE EVENT OBJECT
Here is the example that has been used throughout
the chapter so far with some modifications:
1. The function is called check Length() rather than
checkUsername (). It can be used on any text input.
2. The event object is passed to the event listener.
The code includes fallbacks for IES-8(Chapter13
demonstrates using helper functions to do th is).
3. In order to determine which element the user
was interacting with , the function uses the event
object's target property (and for IES-8 it uses the
equivalent s rcEl ement property).
This function is now far more flexible than the
previous code you have seen in this chapter because:
1. It can be used to check the length of any text
input so long as that input is directly followed by an
empty element that can hold a feedback message
for the user. (There should not be space or carriage
returns between the two elements; otherwise, some
browsers mi ght return a whitespace node.)
2. The code will work with IES-8 because it tests
whether the browser supports the latest features (or
whether it needs to fall back to use older techniques).