Checking if javascript replace() is empty

Question

I've been trying to make a simple bbcode parser, it works very well when the code is right but when there's no code I don't know how to handle it.

Here's my code:

function BBCodeHTML(text) {
    //WEBSITE 1
    code = '<iframe width="10" height="10" src="https://www.videoWebsite.com/video/$1"></iframe>';
    text = text.replace(/\[videoTag\](.*?)\[\/videoTag\]/g, code);
    return text;
    //WEBSITE 2
    code = '<iframe width="10" height="10" src="https://www.videoWebsite2.com/video/$1"></iframe>';
    text = text.replace(/\[videoTag2\](.*?)\[\/videoTag2\]/g, code);
    return text;
    [...]
}

The thing is, if the user just does [videoTag][/videoTag], the $1 thing (I don't know how to call it) is empty and the embed is still shown (without any video).

Is there anyway I can check if $1 is empty and IF IT IS NOT then replace with the embed?

Something like "if $1 = empty { do nothing } else { embed }"

I tried searching for answers but $1 empty etc gives me nothing.

If any mod knows a better title for this question, feel free to edit.

try (.+?) instead of (.*?), *-nothing or more, +-one or more — Grundy
– Grundy, Commented Feb 5, 2014 at 6:33

score 1 · Accepted Answer · 2014-02-05 06:40:47Z

1

Try this regex :

var r = /\[tag\](?!\[\/tag\])(.*?)\[\/tag\]/g;

Let's say whitespaces are considered "empty" :

var r = /\[tag\](?! *\[\/tag\])(.*?)\[\/tag\]/g;

Usage example :

'[tag]  [/tag][/tag][tag]content[/tag]'.replace(r, '<tag>$1</tag>');
// "[tag]  [/tag][/tag]<tag>content</tag>"

The regular expression :

\[tag\]           "[tag]"
(?! *\[\/tag\])   not followed by zero or more whitespaces and "[/tag]"
(.*?)             any char, zero or more times
\[\/tag\]         "[/tag]"

edited Feb 5, 2014 at 6:40

answered Feb 5, 2014 at 6:27

user1636522

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3 Comments

Hizan Over a year ago

Perfect, worked like a charm! Thanks for the explanation too!

user1636522 Over a year ago

@Hizan You could do even better doing this : .replace(/\[(.*?)\](?! *\[\/\1\])(.*?)\[\/\1\]/g, '<$1>$2</$1>'). Will match any BB tag :)

user1636522 Over a year ago

@Hizan I appreciate the comments. Sometimes askers don't give any feedback so, I feel like being blind, this is annoying :/ Keep enjoying :)

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