Question

I want to match a sequence of initials, the whole sequence, which the second regex in the following example does for me correctly. Why is it that I need the “global” flag? The first should also match ONLY the string in its entirety, right? (because of the ^ and the $)

abc = "A.B.C."
abc.match(/^([A-Z]\.)+$/) // result: ["A.B.C.", "C."]
abc.match(/^([A-Z]\.)+$/g) // result: ["A.B.C."]

thanks!

Answer 1

Because the parens do not include the +. So when you do abc.match(/^([A-Z]\.)+$/), the parens match only the first [A-Z]\..

To get the match you want, you don’t need the g flag. Just use match[0] as your result.

var result = abc.match(/^([A-Z]\.)+$/)
if (result) {
    var fullMatch = result[0];
}

Working demo here: http://jsfiddle.net/jfriend00/PXF6U/

See Bergi’s answer for details on why the g flag changes the response like you observed.