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Inconsistent RegExp test results

See original GitHub issue

Hi Svaarala,

I have this code to validate a guid enclosed with braces:

var reGuid = /^\{[0-9A-F]{8}\-[0-9A-F]{4}\-[0-9A-F]{4}\-[0-9A-F]{4}\-[0-9A-F]{12}\}$/g;

var m1 = reGuid.test("{A6BFBB23-4426-4CFB-8D2F-5A642566BF94}");
var m2 = reGuid.test("{A6BFBB23-4426-4CFB-8D2F-5A642566BF94}");
var m3 = reGuid.test("{A6BFBB23-4426-4CFB-8D2F-5A642566BF94}");
var m4 = reGuid.test("{A6BFBB23-4426-4CFB-8D2F-5A642566BF94}");

The expected result is true for all four variables but the output is:

m1=true
m2=false
m3=true
m4=false

Seems the regex state after a test is wrong and cannot restart but a test that fails, resets the internal state correctly.

Regards, Mauro.

Issue Analytics

State:
Created 6 years ago
Comments:6 (4 by maintainers)

Top GitHub Comments

1reaction

svaaralacommented, Jul 2, 2017

@fatcerberus Related, the .lastIndex property of the RegExp instance tracks the offset where to resume from. It has pretty weird semantics if you resume matching a different string though; you can also set it manually if you don’t want to resume matching a string to completion.

1reaction

fatcerberuscommented, Jul 2, 2017

I didn’t realize that’s what the global flag was for. I thought it just meant to match all occurrences (rather than stopping after the first), didn’t know it was also “resumable”.