The option of using pure HTML, sometimes with a touch of CSS, to complement Java Script form validation was until recently unthinkable.
Sure there have been all kinds of whacky plug-ins over the years aimed at achieving this, but never a single standard that we could work towards.
For these examples we have created our own valid/invalid CSS formatting to override the browser default. That's why you may see something like the following: Before you type anything into the box a red marker is shown.As soon as a single character has been entered this changes to a green marker to indicate that the input is 'valid'.Using CSS you can place markers inside or alongside the input box, or simply use background colours and borders as some browsers do by default. On the i Phone/i Pad the different input types are associated with different keyboards, making it easier for people to complete your online forms.In other web browsers they can be used in combination with the .Obviously neither example is very limiting, but it will prevent people from entering completely wrong values, such as phone number, strings with multiple '@'s or spaces.Here is how it appears in Safari (with our CSS formatting to show the (in)valid state): In a similar fashion to the Again, the input box appears as normal: This time the minimum requirement for most browsers is one or more letters followed by a colon. :[\x01-\x08\x0b\x0c\x0e-\x1f\x21-\x5a\x53-\x7f] | \[\x01-\x09\x0b\x0c\x0e-\x7f]) ) \])\z Or you can look here for more solutions.Again, not very helpful, but it will stop people trying to input their email address or other such nonsense. Careful examination of the RFCs associated with email addresses has been conducted repeatedly and has been proven to require the use of recursion in order properly determine the validity of an email address using the full set of RFC specifications.As mentioned above, we can improve on this by making use of the are already implicit so the input has to match the entire expression. If anyone wants to contribute a more thorough expression to test for valid email or url format, feel free to post it using the Feedback option above.. Since it is not possible to recurse when using a regular expression it is also not possible to create a truly accurate regex for doing email address validation.The value, clicking 'down' with the input blank will result in a very large number. The examples posted in these responses are vastly oversimplified when compared against reality.Here is how the two inputs are displayed in Safari: and in Opera: They are currently not supported in Firefox 4 Beta. For example it is perfectly valid for an email address to go to the MX handler for a top level domain.If you want to restrict the input of a text field to numbers without having the up/down arrows associated with the input box, you can always just set the input type to of "\d " (one or more numbers). So something along the line of [email protected] would be perfectly valid! Anyone out there know how to adjust the url validation so that it will accept inputs in the following format: no need to force a user to input or https:// You can find a comparison of some interesting regexes for validating URLs here.