Question

I have a string of this format

1.0.x.0

I have to write a regex in javascript that automatically increment the x— How to do it?

Note, the string given will always be of that format– no need to test for format validity…

Answer 1

Try this:

"1.0.123.0".replace(/(\d+\.\d+\.)(\d+)(\.\d+)/, function($0, $1, $2, $3) {
    return $1 + (parseInt($2) + 1) + $3;
});