Recursive regex pattern in JavaScript

Question

I know it's going to be a VERY obvious answer, but I can't find anything on how to do this.

I'm trying to unescape < and > within an HTML string

My test output string is essentially:

```php
&gt;h2&lt;Heading2&gt;/h2&lt;
```

`&gt;h2&lt;Heading2&gt;/h2&lt;`

&gt;h2&lt;Heading2&gt;/h2&lt;

So in this example we have Github flavoured Markdown, a regular code markdown snippet, and then raw text all with the same HTML tag. I want to unescape the raw tag (the third one) to actually become a link. The ideal output would be something like this.

```php
&gt;h2&lt;Heading2&gt;/h2&lt;
```

`&gt;h2&lt;Heading2&gt;/h2&lt;`

<h2>Heading2</h2>

I'm getting stuck at getting multiple > in the same line.

Current regex:

/(?:.*?(&gt;))/

This will get the first entry.

/(?:.*?(&gt;))/g

This one gets the second entry. I want it to be able to get EVERY entry. Then, it's just a matter of throwing the tick pieces.

/(?:```|`)(?:.*?(&gt;)).*?(?:```|`)/gs

I can only replace the > that are NOT within ```{here}``` and `{here}` — Eric Holmes
– Eric Holmes, Commented Feb 6, 2015 at 21:25

hwnd · Accepted Answer · 2015-02-06 22:29:51Z

2

If you're intending on using a regular expression for this task, you can consider the following:

var r = s.replace(/((`(?:``)?)[^`]*\2)|&gt;/g, '$1<')
         .replace(/((`(?:``)?)[^`]*\2)|&lt;/g, '$1>')
         .replace(/`[<>]+/g, '`');

Working Demo

edited Feb 6, 2015 at 22:29

answered Feb 6, 2015 at 21:44

hwnd

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3 Comments

Eric Holmes Over a year ago

Thanks hwnd! May I ask why the second replace is necessary? I see the issue, but I'm wondering if we can get it to not add the < after the trailing tick.

Eric Holmes Over a year ago

Either way, this will solve it I think, and just run a second with < replaced by $1>

Eric Holmes Over a year ago

Thanks so much! I may end up switching to using AJAX and using my PHP parser, as it's much more complete, but this will work great for now, thanks!

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