Regular Expression for ASP.NET ID Using Javascript

Question

I am trying to extract the word "need" from this string.

ctl00_ctl00_ContentMainContainer_ContentColumn1__needDont_Panel1

I have tried [__]([.]?=Dont)

This is using javascript .match()

I have even tried to use http://gskinner.com/RegExr/ but just can't solve this one. Thanks for the help!

Answer 1

This will accomplish what you're looking for:

__(.*)(?=Dont)

You seem to be mixing up what a character class - square brackets [] - does, instead you should be using regular brackets ().

In your regex [__] will only match a single underscore _ and [.] will match a single period.

Answer 2

Your error is writing [__] instead of __ (without the braces). [__] matches only a single underscore, so it will match _ctl00_ContentMainContainer_ContentColumn1__need.

[.] is also wrong. You should use something like: [^_]+ (anything except underscore).

Answer 3

(?<=__)\w+(?=Dont)

Matches all alpha-numbers between __ and Dont

Edit

Sorry, I havent noticed word JavaScript. It does not support lookbehind, so __(\w+)(?=Dont) can be used there. If Regex should match even when nothing comes between __ and Dont use "\w*" instead of "\w+". Be careful with ".*" because dot matches almost all characters, do you allow spaces in ID?

I haven't noticed