NOT a specific word at ending in regex

Question

I have those strings:

"/page/test/myimg.jpg"
"/page/test/"
"/page2/test/"
"/page/test/other"

I want true for all strings starting with /page/test except when it ends with .jpg.

Then I did: /^\/page\/test(.*)(?!jpg)$/. Well, it's not working. :\

It should return like this:

"/page/test/myimg.jpg" // false
"/page/test/" // true
"/page2/test/" // false
"/page/test/other" // true

You can't really do negative look ups like that without doing a bit of trickery. Take a look at http://stackoverflow.com/questions/406230/regular-expression-to-match-string-not-containing-a-word where this has been answered thoroughly. — ranieuwe, Aug 23 '13 at 16:29

score 4 · Answer 1 · answered Aug 23 '13 at 23:24

4

Easily done with JavaScript:

/^(?!.*\.jpg$)\/page\/test/

answered Aug 23 '13 at 23:24

ridgerunner

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+1 I didn't know that javascript doesn't support look behinds, but does support look aheads. – Bohemian Aug 24 '13 at 00:09

Bohemian · Accepted Answer · 2013-08-23T17:37:40.880

3

Use a negative look behind anchored to end:

/^\/page\/test(.*)(?<!\.jpg)$/

For clarity, this regex will match any input that *doesnt end in .jpg:

^.*(?<!\.jpg)$

Edit (now must work in JavaScript too)

JavaScript doesn't support look behinds, so this ugly option must be used, which says that at least one of the last 4 characters must be other than .jpg:

^.*([^.]...|.[^j]..|..[^p].|...[^g])$

edited Aug 23 '13 at 17:37

answered Aug 23 '13 at 16:30

Bohemian

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Thanks! Just miss the `<` at `?<!`. For complete explanation, what can I use in javascript regex for `?<!`? – Ratata Tata Aug 23 '13 at 16:43
You can use any limited-length expression. If you need `.*`, limit it eg `.{0,99}` – Bohemian Aug 23 '13 at 16:46
I am sorry. `?<!` does not exists in javascript regex. Do you know a substitute for it (if it at least exists)? I'm doing this same thing in .htaccess and javascript. – Ratata Tata Aug 23 '13 at 17:14
Then that is a different question - I have updated the question tags and provided an answer. – Bohemian Aug 23 '13 at 17:37
No ugly option needed (and lookbehind is not required). See my simple answer. – ridgerunner Aug 23 '13 at 23:28

NOT a specific word at ending in regex

2 Answers2

Edit (now must work in JavaScript too)