Javascript RegExp parse URL make hyperlinks ignore img src

Question

I am not very good with Regular Expressions, some times I can figure them out but...

I need to parse text strings (for a chat room project).

So as you would imagine any pasted URLs need to be converted to click-able hyper links.

I use this RegExp for that, cobbled together from examples I have found on the net. It appears to work quite well :

/[A-Za-z]+:\/\/[A-Za-z0-9-_]+\.[A-Za-z0-9-_:~;@'#%&.=\]\[\*\$\!\?\/\,]+/g

Now another part of my project has to insert images in other words :

<img src="http://path/to/image" alt="alt" />

So I need the reg exp to ignore those, and I tried this :

/(?!src=")[A-Za-z]+:\/\/[A-Za-z0-9-_]+\.[A-Za-z0-9-_:~;@'#%&.=\]\[\*\$\!\?\/\,]+/g

But it doesn't work. Perhaps my expression is faulty or I am going about it the wrong way.

I may just mask out 'src="http' and run my expression then reapply what I masked out.

But before I do that I thought I would see if anyone here has any ideas.

Many thanks.

I'm still unsure what you're trying to do. Where will the images be inserted and what is the regex you've written supposed to do? — Aram Kocharyan
– Aram Kocharyan, Commented Jun 7, 2012 at 13:27
This regex looks like you just blindly copy-pasted from the one above. I would read up on javascript RegExp and play around with this. regexpal.com — tronbabylove
– tronbabylove, Commented Jun 7, 2012 at 13:28
The first expression identifies urls and I later use it to make those urls into hyper links. There are no images to be inserted using the expression, as I said I want to ignore already encoded images. If you look carefully you will see that the second expression has (?!src=") at the beginning... — Rog
– Rog, Commented Jun 7, 2012 at 13:30
Tronbabylove, it appears you blindly commented without taking a good look ;) — Rog
– Rog, Commented Jun 7, 2012 at 13:31

beerbajay · Accepted Answer · 2012-06-07 13:51:09Z

1

(?!src=")

is a negative lookahead, what you want there is a lookbehind, which javascript does not support.

answered Jun 7, 2012 at 13:51

beerbajay

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1 Comment

Ahh ok thanks, at least I learnt something new today. I will use my masking idea then. Thanks for your reply :)