User Guide

144 Chapter 9 Building Dynamic Forms
Input Validation with JavaScript
In addition to native ColdFusion input validation using the validate attribute of the
cfinput and cftextinput tags, the following tags support the onvalidate attribute,
which allows you to specify a JavaScript function to handle your
cfform input
validation:
•
cfgrid
• cfinput
•
cfslider
• cftextinput
•
cftree
ColdFusion passes the following JavaScript objects to the JavaScript function you
specify in the
onvalidate attribute:
• form_object (the form)
• input_object (the tag whose value is being validated)
• object_value (the value to validate)
Handling failed validation
The onerror attribute allows you to specify a JavaScript function to execute if a
validation fails. For example, if you use the
onvalidate attribute to specify a
JavaScript function to handle input validation, you can also use the
onerror
attribute to specify a JavaScript function to handle a failed validation (that is, when
onvalidate returns a false value). If you are using the validate attribute you can
also use the
onerror attribute to specify a JavaScript function handle validation
errors. The following
cfform tags support the onerror attribute:
•
cfgrid
• cfinput
• cfselect
•
cfslider
• cftextinput
• cftree
ColdFusion passes the following JavaScript objects to the function in the onerror
attribute:
• form_object
• input_object
• object_value
• error message text
Example: validating an e-mail address
The following example validates an e-mail entry. If the string is invalid it displays a
message box. If the address is valid it redisplays the page.