Wanted to see how hard is it to display a good looking opt in for people to sign up for free picks with the field for their number being required where the system may be able to read the number and if it's not a valid 10 digit number than it defaults and makes them input the correct phone number.
Are you looking to carry out server side validation. Have you though of client side validation using JS?
Simply use a RegularExpressionValidator component and ensure that you do a serverside Page.IsValid check before proceeding to make sure people arent trying to bypass the clientside javascript checking.
Javascript is not bad for SEO unless you have mountains of it at the begining of the page or that it prevents navigation if javascript is turned off. When using .Net controls (or at least the out the box ones) 99% of the javascript is placed in external files and so cannot create the mounts of javascript and as the controls in question are validation on form submission it naturally isnt going to restrict site navigation.
No, javascript is not bad for SEO. That is a myth that goes back to a time in the early 2000s when Google had a difficult time reading javascript. Sites using javascript navigation did not always get their internal links to pass PR. That issue is long gone, but statements about it linger still.
No it isn't hard. If IsNumeric(PhNum) And Len(PhNum) = 10 Then 'valid Else 'invalid End If Code (markup): Where PhNum is the variable that contains the phone number. I wouldn't bother with javascript validation unless you are expecting really heavy traffic.
Javascript isn't bad for SEO, However you shoudl try your best to make the journey of search engine spiders as pleasent as possible. Javascript canbe vital for a websites functionality, however if your javascript code goes into hundreds of lines. This means there are 100's of lines in between your keywords in the content & the header of the page. It is always best to use Unobtrusive JavaScript. Try searching for "Unobtrusive JavaScript" on google. Other members who have posted here are correct that Javascrtipt is not bad for SEO, but as a SEO consultant I always advise my clients to use Unobtrusive JavaScript.If you have any questions please feel free to ask.