Possible Duplicate:
Javascript regex returning true.. then false.. then true.. etc
var r = /\d/g;
var a = r.test("1"); // will be true
var b = r.test("1"); // will be false
console.log(a == b); // will be false
Please explain to me why the result of r.test("1") alternates with each call?
I was able to work around the issue I was having by removing the g modifier. However I would still like to understand why this happens.
When you're using /g, the regex object will save state between calls (since you should be using it to match over multiple calls). It matches once, but subsequent calls start from after the original match.
(This is a duplicate of Javascript regex returning true.. then false.. then true.. etc)
lastIndex is a property of the regex, not the string. In Perl, by contrast, it's associated with the string (the pos property), while in Java it's maintained by Matcher object. lastIndex is a source of much frustration: blog.stevenlevithan.com/archives/fixing-javascript-regexp
