More efficient regex

Question

I am an amateur with regular expressions, but I have a need to extract a piece of string in javascript.

My current (working) code is:

var txt='Icon/something/0.gif'; var re1='.*?'; var re2='(?:[a-z][a-z]+)'; var re3='.*?'; var re4='((?:[a-z][a-z]+))'; var p = new RegExp(re1+re2+re3+re4,["i"]); var m = p.exec(txt); var word = m[1]; //something

However I can't imagine that us the most efficient way of doing it.

What I need to do is extract "something" from a string like this:

Icon/something/0.gif

or "somethingelse" from:

Icon/somethingelse/10.gif

Is there a more compact regex I can use?

RegExp flags are strings, not arrays, and unless you have a dynamic "selector", there's no reason to manually construct RegExps like that instead of using a simple literal. Finally, the exec() method is rarely used for a few long-winded reasons; i suspect you would find "".match() or "".split() more to your liking. — dandavis
– dandavis, Commented Jul 15, 2014 at 17:25
Logically, the regex you build is completely equivalent to [a-z][a-z].*?([a-z][a-z]+). Your are extracting the first substring made of lower-case letters that follows two lower-case letters and one or more arbitrary characters. To me, that seems to be not exactly what you want to do. — JohnB
– JohnB, Commented Jul 15, 2014 at 17:40

royhowie · Accepted Answer · 2014-07-15 17:48:22Z

7

Try this to get the second element split by the forward slashes (/):

txt.split("/")[1]

edited Jul 15, 2014 at 17:48

royhowie

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answered Jul 15, 2014 at 17:24

Pablo Matias Gomez

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2 Comments

sharf Over a year ago

Other answers are correct but I like this solution better...can't believe I didn't think of this. Thanks!

Casimir et Hippolyte Over a year ago

-1, This way doesn't check if the format is correct (i.e. Icon/WhatYouNeedToFind/Integer.gif)

JohnB · Accepted Answer · 2014-07-15 17:28:24Z

/\/([^\/]*)\//

will find the first substring of non-/-characters that is surrounded by / characters.

bob_flem · Accepted Answer · 2014-07-15 17:37:08Z

Using substring:

var get=string.substring(string.indexOf("Icon/")+5,string.indexOf("/",string.indexOf("Icon/")+5))

Where string would be Icon/anythingHere/10.gif

var a = string.indexOf('/'); var b = string.indexOf('/',a+1); var result = string.substr(a+1,b-a-1);

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