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How can I format this so it only checks if my string starts with the letter "a" or "b" and also accepts misc. characters after this (numbers or letters)?

Just need to make sure it starts with the letter a or b, the rest is ok and will have more characters.

mystring.match(/^D\d{22}$/i
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3 Answers

up vote 1 down vote accepted

If you only want to match whether the string starts with a or b, it would be a completely different expression:

/^[ab][a-z\d]*/i.test(mystring)

Edit: Updated to much arbitrary characters afterwards.
Edit2: Restricted to numbers and letters.

Of course you can also combine this with any other expression if you want to.

This is great source to learn about regular expressions.

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Does this take in consideration capital letters? – detonate Mar 8 '11 at 22:34
@detonate: Yep, that is what the i flag is for. You use the same in your code. – Felix Kling Mar 8 '11 at 22:41
@detonate: Or if you don't want capital letters to match, then you have to remove the i. Unfortunately your comment is not clear enough in this case. – Felix Kling Mar 8 '11 at 22:48
Felix, It will not let me use other characters after the 1st letter string checkup. Edited the question accordingly now. – detonate Mar 8 '11 at 22:50
@detonate: Ah stupid mistake of mine... updated my answer. – Felix Kling Mar 8 '11 at 22:56
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This should work "/^[ab][A-Za-z0-9_-]*$" for generic string to start with "a" or "b" use link to verify RegEx online.

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up vote 1 down vote

"Start with a or b" would be in regex-speech:

/^[ab]

then you put the rest of your pattern match.

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Edited my question. – detonate Mar 8 '11 at 22:48
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