JavaScript (RegExp)

[Lugubrious]

Could someone explain the RegExp Object? I keep reading the tutorial and I still can't wrap my mind around it. Preferably explain using examples; I don't like conceptual things as much as practicality. Thank you so much to whichever person explains this. I catch on to things easily, usually.

[Bennett 🚀]

First of all, are you just trying to grab stuff and save it from Proboards or from somewhere else? Assuming it's for Proboards, you would use something like this:

<script type="text/javascript"><!--
var td=document.getElementsByTagName('td');
for(t=0; t<td.length; t++){
if(td.item(t).innerHTML.match(/(.?+)\ some words after what you're looking for/i){
var amount = RegExp.$1;
document.write(amount);
}
}
//--></script>


So the most usual RegExp to use is (.?+)\ or (\d+)\ (correct me on the proper use of the d one) The (\d+)\ is used to grab numbers, and the (.?+)\ is used for everything else.

If you need more examples, just look in some PM bar codes, and such.

[Lugubrious]

Thank you very much! That helped a lot. I'll go check those out and hash it out.

[Bennett 🚀]

I have one, be sure to look at that. And some more complicated RegExp can be found in like miniprofile and info center hacks.

EDIT: I suggest reading this tutorial. This is what got me to learn it:
forum.sz-ex.com/index.cgi?board=codetuts&action=display&thread=9776

[Lugubrious]

That tutorial is absolutely fantastic. It is helping fill in the gaps that come from teaching yourself everything. ^.^ Thank you so much. If I have more questions while I play around with it, I'll post 'em here. For some reason the tutorials I've used for a while now seem to make that very confusing. I'll follow the tutorial for a bit.

[Bennett 🚀]

Yeah, that's where I finally figured out RegExp.. everything else I got by myself.

[coolcoolcool]

Something else you might want to know. The letters i and g after the second / are modifiers. The i stands for case-insensitive and the g means global or more than once (keeps searching after first occurence.

The regular expressions part of it can get rather complicated, so the best method is usually to use a resource (like a tutorial) to look back on when doing them .. or any programming for that matter.

Good luck!

[Chris]

I haven't read the entire thing but it looks pretty thorough. I however would like to point out a tiny error in the regex section which might give those trying to learn the wrong idea...

/The dog is (.+?)\./i

The first forward slash ( / ) defines the beginning of a regular expression pattern, and the second forward slash defines the end of the pattern. First we check to see if the innerHTML of the div matches "The dog is (.+?)\./i". So, what does the (.+?) mean? The parentheses ( ) mean you are looking for a group of characters inside the parentheses. If you use parentheses, the contents of the parentheses will also be saved for use later, which you will learn about in a moment. The . (dot) defines any character other than a newline. The + (plus sign) defines that one or more instances of the pattern may occur. The ? defines that one or zero instances of that pattern may occur. So since the . (dot) defines any character, the + (plus sign) says that more than one character can occur in the pattern, which is obviously necessary in most cases. Then the ? says that zero or one instance of THAT pattern may be matched. I'll break it down further for you, since I'm having a hard time writing this, and you are probably having a hard time understanding. If it were simply (.), that would match one of any character other than a newline. If it were (.+), it could any character or any group of characters. And the ? just says that the pattern may or may not occur, so it is a good idea to add it just in case the pattern doesn't occur. So (.+?) matches ANY group of characters (other than a newline, of course), it took me a while to explain that, eh?

It's a subtle difference but in this particular case the ? is functioning as a greed modifier not an optional. The greed modifier basically says stop as soon as you find a match for the pattern rather than the usual behavior of extending the match until it can go no farther.

For example if that regex was run against the following sentence:

The dog is commonly referred to as man's best friend. The loyalty displayed by this animal is said by some to be superior to any human friend they've ever had.

With the greed modifier, the match would stop at the first period, without the greed modifier it would continue on to the second period.
The decision to include it or not would depend on how much data you wish to capture and not whether that data is optional. If there was a question mark to the right of the closing parenthesis (.+?)? then that would be an optional for what was contained in the parentheses.