Javascript：使用正则表达式在最后一次出现的字符串和另一个字符串之间找到字符串

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.

Answer 1

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 "

Answer 2

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, eg \\s,;\\. to not capture those, if you only want the word/s in between.

Cheers.

Answer 3

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

Answer 4

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

1. '(to)(?!.*\\1)' its matching the last to
2. (.*) 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]);