Regex, how do I say, match everything but one word?

Question

Using regex I'm trying to match anything BUT one word, that word being '/item/'.

([^/]+)

That matches anything (true), but I'd like it to be false if the word '/item/' is in there.

Would I have to do something like this?

([^/]+|!/item/)

Where the pipe is 'OR' and the ! is 'is not,' this example that I've written is definitely the wrong syntax... I'm a newb when it comes to regex.

Update:

Here is the live example:

^(category)/([^/]+)/([^/]+)/([^/]+)/([^/]+)/?$

category/all-weather-wicker/bermuda/table/2977/ should pass

category/all-weather-wicker/bermuda/item/2977/ should fail

Thanks for your help!

i think the pipe should mean and...otherwise you want (anything or anything not item) which is anything — Logan Murphy, May 06 '14 at 16:31
Why not just check if the word 'item' is in the string? `str.indexOf("item");` returns -1 if it's not present, otherwhise it returns a positive number. — Michel, May 06 '14 at 16:47
Building on what @Michel said, check out the second example of the answer from here: https://stackoverflow.com/questions/177719/javascript-case-insensitive-search It doesn't require regular expressions and it wont require sanitizing user input to exclude metacharacters. — Mr. Llama, May 06 '14 at 16:57
possible duplicate of [Regular expression to match string not containing a word?](http://stackoverflow.com/questions/406230/regular-expression-to-match-string-not-containing-a-word) — John Dvorak, May 06 '14 at 16:58

hwnd · Accepted Answer · 2014-05-06T17:43:31.853

2

If your strings will always be consistent, you could use a Negative Lookahead here.

^(category)/([^/]+)/([^/]+)/((?:(?!\bitem\b).)+)/([^/]+)/?$

See live demo

edited May 06 '14 at 17:43

answered May 06 '14 at 17:26

hwnd

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Pedro Lobito · Answer 2 · 2014-05-06T17:01:22.793

Try this:

var subject = "category/all-weather-wicker/bermuda/item/bermuda-end-table/table/2977/";
if (/^category(?!.*?\/item\/\d+\/).*?$/im.test(subject)) {
    console.log("passed");
} else {
    console.log("failed");
}

LIVE DEMO

EXPLANATION:

Assert position at the beginning of a line (at beginning of the string or after a line break character) (line feed, line feed, line separator, paragraph separator) «^»
Match the character string “category” literally (case insensitive) «category»
Assert that it is impossible to match the regex below starting at this position (negative lookahead) «(?!.*?/item/\d+/)»
   Match any single character that is NOT a line break character (line feed, carriage return, line separator, paragraph separator) «.*?»
      Between zero and unlimited times, as few times as possible, expanding as needed (lazy) «*?»
   Match the character string “/item/” literally (case insensitive) «/item/»
   Match a single character that is a “digit” (ASCII 0–9 only) «\d+»
      Between one and unlimited times, as many times as possible, giving back as needed (greedy) «+»
   Match the character “/” literally «/»
Match any single character that is NOT a line break character (line feed, carriage return, line separator, paragraph separator) «.*?»
   Between zero and unlimited times, as few times as possible, expanding as needed (lazy) «*?»
Assert position at the end of a line (at the end of the string or before a line break character) (line feed, line feed, line separator, paragraph separator) «$»

jsuna · Answer 3 · 2014-05-06T16:57:13.643

0

Hi you can try the reverse logic, might be easier to look for the existance of '/item/'

javascript...

var st1 = 'here is a string with /item/ in it';
var m = st1.match(/\/\bitem\b\//g);
m = (m !== null)?false:true;
console.log(m);

NOTE: don't forget to escape your "/" like "\/"

here is a fiddle to demonstrate...

http://jsfiddle.net/KF4De/

edited May 06 '14 at 16:57

answered May 06 '14 at 16:51

jsuna

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Regex, how do I say, match everything but one word?

3 Answers3