Javascript: Regex to find string between last occurrence of a string and another string

Question

I want to find the text occurring between the last occurrence of the word "to" in a sentence and another word "Mary".

So, for the sentence

"I went on Friday morning to bed, then to arrive for that thing and then to beloved Mary"

My regex should match the string "beloved".

I've tried the following code:

var str = "I went on Friday morning to  bed, then to arrive for that 
thing and then to beloved Mary";
var r = /to\b(.*)Mary/g
var match = r.exec(str);
console.log(match);

And am using the global flag as I want to match all occurrences of the word "to". I'm expecting it to return an array of strings, with one of them being the string "beloved" but the output I get is:

["to bed, then to arrive for that thing and then to beloved Mary", " bed, then to arrive for that thing and then to beloved "]

Jsbin here:

http://jsbin.com/puyijo/edit?js,console

Any suggestions?

EDIT: The word "Mary" is not necessarily at the very end of the string.

Is Mary at end of string ?

Rahul
– Rahul

2017-05-03 12:55:35 +00:00
Commented May 3, 2017 at 12:55 — Rahul
– Rahul, Commented May 3, 2017 at 12:55
Not necessarily - question edited

Binaromong
– Binaromong

2017-05-03 12:57:19 +00:00
Commented May 3, 2017 at 12:57 — Binaromong
– Binaromong, Commented May 3, 2017 at 12:57
/.*to\b *(.*?) *\bMary/g

logi-kal
– logi-kal

2017-05-03 12:58:19 +00:00
Commented May 3, 2017 at 12:58 — logi-kal
– logi-kal, Commented May 3, 2017 at 12:58

slim · Accepted Answer · 2017-05-03 13:05:44Z

2

Since you're looking for the last occurrence of to, you can greedily consume any other instances of to with .*:

 /.*to\b(.*)Mary/

With the requirement you've described, the /g is not necessary, since there can only be one "last occurrence of to"

answered May 3, 2017 at 13:05

slim

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Comments

logi-kal · Accepted Answer · 2017-05-03 13:04:32Z

0

Regex parser is greedy by default, so it will first try starting from the first occurrence of to.

You need to discard all the previous characters using .*:

/.*to\b *(.*?) *\bMary/g

answered May 3, 2017 at 13:04

logi-kal

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Comments

prasanth · Accepted Answer · 2017-05-03 13:09:42Z

0

Try this pattern /(to)(?!.*\1)(.*)Mary/g

'(to)(?!.*\1)' its matching the last to
(.*) is find the text between to and Mary

Demo Regex

var str = "I went on Friday morning to  bed, then to arrive for that thing and then to beloved Mary";
var r = /(to)(?!.*\1)(.*)Mary/g;
var match = r.exec(str);
console.log(match[2]);

answered May 3, 2017 at 13:09

prasanth

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Comments

Ovidiu Dolha · Accepted Answer · 2017-05-03 13:23:59Z

0

You need to match something before the actual to-Mary sequence:

var r = /.+to(.+)Mary/

You also do not use the group flag.

Then your matching group is the 1st group: match[1].

Note that if you might want to trim the result, or add some other chars outside the group in the regex, e.g. \s,;\. to not capture those, if you only want the word/s in between.

Cheers.

edited May 3, 2017 at 13:23

answered May 3, 2017 at 13:02

Ovidiu Dolha

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