How to wrap a group of words with tags, JavaScript Replace Regular Expressions

Question

I am trying to wrap some words with HTML tags, for that I am using regular expressions. I am almost there: This is my regexp ``` /((apple|banana|cherry|orange)\b\s?)+/gi ``` and this is my replacement: ``` $& ``` which works perfectly for my example text: ``` Apple Banana apple cherry, Cherry orange and Oranges Apple, Banana ``` the result being: ``` Apple Banana apple cherry, Cherry orange and Oranges Apple, Banana ``` I could be pragmatic and live with this but I would reaaaaaally like to have it perfect and not include the space after the final match. i.e. my perfect result would be (see the tag shifted left after "Cherry orange"): ``` Apple Banana apple cherry, Cherry orange and Oranges Apple, Banana ```

Accepted Answer

JavaScript doesn't support lookbehind. This is a shame, as we could have done:

```
// doesn't work in JavaScript:
/((apple|banana|cherry|orange)\b\s?)+(?<!\s)/gi 
```

What we can do, however, is to move the white-space to the beginning, and add a negative lookahead (so the catch must not start with a white-space):

```
/(?!\s)(\s?\b(apple|banana|cherry|orange)\b)+/gi
```

A slight difference from your code is that I also added `\b` to the beginning of the pattern, so it wouldn't catch `apple` from `Snapple`.

How to wrap a group of words with tags, JavaScript Replace Regular Expressions

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