Javascript regex match fail

Question

Can someone explain why this does not work? (I am using Chrome Developer Console)

pattern  
-> "/Xmp\.MP\.RegionInfo\/MPRI:Regions/"
key
-> "Xmp.MP.RegionInfo/MPRI:Regions[1]"
key.search(pattern)
-> -1
key.search(/Xmp\.MP\.RegionInfo\/MPRI:Regions/)
-> -1
"Xmp.MP.RegionInfo/MPRI:Regions[1]".search(pat)
-> -1
"Xmp.MP.RegionInfo/MPRI:Regions[1]".search(/Xmp\.MP\.RegionInfo\/MPRI:Regions/)
-> 0

It make absolutely no sense to me that the search does not match if i use the variables....

I can't reproduce this behavior: key.search(/Xmp\.MP\.RegionInfo\/MPRI:Regions/) outputs -1. I get 0 instead, as is expected. — user1726343
– user1726343, Commented Nov 20, 2012 at 11:13

David Hellsing · Accepted Answer · 2012-11-20 11:11:48Z

2

It looks like pattern is a String in your first example, it needs to be a RegExp object:

var pattern = /Xmp\.MP\.RegionInfo\/MPRI:Regions/
var key = "Xmp.MP.RegionInfo/MPRI:Regions[1]"

key.search(pattern); // equals 0

If you want to convert a string to a regex, use the RegExp constructor (but remove the slashes):

var pattern = new RegExp("Xmp\.MP\.RegionInfo\/MPRI:Regions");

http://jsfiddle.net/CpEjA/

edited Nov 20, 2012 at 11:11

answered Nov 20, 2012 at 11:06

David Hellsing

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1 Comment

user1726343 Over a year ago

No it doesn't, but it is in the question. Can't explain it.

barryhunter · Accepted Answer · 2012-11-20 11:06:47Z

0

In your example pattern appears to be a string. You need it to be a RegExp object.

answered Nov 20, 2012 at 11:06

barryhunter

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Comments

Krzysztof · Accepted Answer · 2012-11-20 11:07:55Z

0

In first case your pattern is wrapped in quotes, so it is string. In second case it is without quotes -> it is RegExp object.

answered Nov 20, 2012 at 11:07

Krzysztof

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