Accelerated DOM Scripting with Ajax, APIs, and Libraries

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Jonathan Snook, Aaron Gustafson, Stuart Langridge, and Dan Webb

"Accelerated DOM Scripting with Ajax, APIs, and Libraries"

So the following means ???if the value in this field does not match
the regexp,??? and that??™s when the error message needs to be displayed:
if (fld.value.search(re) == -1)
The page has been built so that the part containing this field looks like the following:

Date of birth (DD/MM/YYYY)

So each field has an associated span for displaying the error messages. The DOM tree for
that snippet, then, would be that the , the , and the are all children of
the

element. So the best way to get a reference to the is with the following:
fld.parentNode.getElementsByTagName('span')[0]
At that point, you can simply set the appropriate error message to display by setting the
innerHTML of the . Similarly, when the if statement that checks the field against the
regexp returns something other than -1, it means that the field value is correct, so you can
remove the error message by setting the innerHTML of to blank.
Finally, you add a cross-browser addEvent() function and wrap the whole block of
JavaScript code up in a simple object (so that the function names and variables don??™t collide
with any other scripts you happen to be loading), and tidy up the PHP a tiny bit (printing a
field with a function instead of having all the fields directly inline in the page), and you have
Listing 7-2.

Pages:
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Schaum's Outline of Principles of Computer Science (page 253) Practical Reporting with Ruby and Rails (page 290) Foundation Flex for Designers (page 146)

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Jonathan Snook, Aaron Gustafson, Stuart Langridge, and Dan Webb

"Accelerated DOM Scripting with Ajax, APIs, and Libraries"