Negative Lookahead to find lat matched word in a sentence

Question

I want to find last matched word in a sentence using regex. I searched for this functionality and found negative lookahead.

Ex: To find "foo" in "This foo is not same as the foo"

Here i need to find last matched "foo" 's index. For this I am using javascript search function with search(regex) where regex is foo(?!.*foo)

problem is that search is not returning correct index (it may be regex issue).This feature is same as chrome's find feature where up arrow finds previous match.So I want to know if i need to change my regex ?

Thanks

Please add the code you have. Look [here](https://jsfiddle.net/272j97cd/), `28` looks correct to me. — Wiktor Stribiżew, Dec 01 '16 at 11:52
thanks Wiktor again :) I was using substring in wrong way (substring to discard last previous matched word) — Bhuwan, Dec 01 '16 at 12:03
@WiktorStribiżew for that reason I simply suggested using `String.prototype.lastIndexOf()` — Yosvel Quintero, Dec 01 '16 at 12:07
yes but i need it to be case sensitive also and there might be some issues with localizations — Bhuwan, Dec 01 '16 at 12:08
@Bhuwan: What substring? Please *add the code you have into the question*. — Wiktor Stribiżew, Dec 01 '16 at 12:13
You right @Bhuwan, for case sensitive here is an answer that could help http://stackoverflow.com/questions/273789/is-there-a-version-of-javascripts-string-indexof-that-allows-for-regular-expr — Yosvel Quintero, Dec 01 '16 at 12:16
@wiktor suppose you have found first last matched word now when you want to find next previous you need to remove already found last matched word from sentence. So I was taking substring to remove last match from sentence — Bhuwan, Dec 01 '16 at 12:23

score 1 · Answer 1 · answered Dec 01 '16 at 11:53

1

To find last matched "foo" 's index. You can use String.prototype.lastIndexOf()

var lastIndex = 'This foo is not same as the foo'.lastIndexOf('foo');

console.log(lastIndex);

answered Dec 01 '16 at 11:53

Yosvel Quintero

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What if OP needs to find a `foo` that is only a whole word? – Wiktor Stribiżew Dec 01 '16 at 11:54
1

http://regexr.com/3eplj it is working fine.They are using match() javascript function but i need index of matched word so using search function – Bhuwan Dec 01 '16 at 11:55
If `foo` is the only whole word the returned last index will be `0` instead of `-1` that returns if no found.. – Yosvel Quintero Dec 01 '16 at 12:18

Negative Lookahead to find lat matched word in a sentence

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