402046 - RegExp test() returns inconsistent results

Status: VERIFIED DUPLICATE of bug 98409

(Core :: JavaScript Engine, defect)

Description

[Jay Knight]

User-Agent:       Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.8.1.8) Gecko/20071008 Firefox/2.0.0.8
Build Identifier: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.8.1.8) Gecko/20071008 Firefox/2.0.0.8

When doing a javascript regexp test, it can return true once, but if run again it can return false.

Reproducible: Always

Steps to Reproduce:
1. See attached testcase
2. Enter a value containing character other than letters or numbers
3. Click the "Test Value" link
4. Click it again.
Actual Results:  
first time, you get the error message, but the second time you do not.

Expected Results:  
Gives the error message each time.

Comment 1

[Jay Knight]

Attachment: HTML/Javascript testcase

Comment 3

[Jesse Ruderman]

I can reproduce with the command-line js shell, using:

function f(s) { return /[^A-Z0-9]/gi.test(s); }
f("@");
f("@");

It returns true the first time and false the second time.

This might be related to bug 98409, which is widely considered to be a bug in the ECMAScript 3 specification: you don't get a new instance of the regexp object each time f() runs.

This only happens if the regular expression has the 'g' flag.  I don't know whether it's intentional that the 'g' flag affects the .test() function; http://developer.mozilla.org/en/docs/Core_JavaScript_1.5_Reference:Global_Objects:RegExp:test  doesn't mention it.

js> r = /a/g;
/a/g
js> s = "aba";
aba
js> r.test(s);
true
js> r.test(s);
true
js> r.test(s);
false

If that behavior of test() is correct and intentional, then this is a dup of bug 98409.

Comment 4

[Jesse Ruderman]

Explanation in bug 225408 comment 2.