javascript - Regular expression for unique number.

Solution:

You can use character class[VX], it'll match a single character from it.

^[1-9][0-9]{8}[VX]$
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Or,OR condition as follow

^[1-9][0-9]{8}(V|X)$
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Update:

To match the alphabets case-insensitively, usei flag or the lowercase characters can also be added in class

^[1-9][0-9]{8}[VvXx]$
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Solution:

You can also try something simpler (unless the leading number cannot be 0)

\d{9}[VX]
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Solution:

Why not justd{9} ?/\d{9}(V|X)/ seems easier.

var test = "qwerty000000000Xqwerty";

console.log(test.match(/\d{9}(V|X)/));
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http://jsfiddle.net/u5gmfjeL/1/ - matches830363670V as well.

case insensitive add/i -> /\d{9}(V|X)/i -> http://jsfiddle.net/u5gmfjeL/2/

Solution:

You could do:

^[1-9][0-9]{8}[VX]$
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Or more generically if the suffix were more than one character you could use groups. As it appears you are using POSIX Extended Regular Expression (ERE) syntax, you can also use parenthesis for groups, like:

^[1-9][0-9]{8}(V|X)$
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Link to ERE syntax

Link to JavaScript Regex standard