Thanks so much for this. The guide is just what I was looking for. I'll spend some time on this today and post again when i have success or hit a wall.

In Firebug, if I select an object like the title, I have the option to copy some html strings. There is an option to copy the "unique selector", but this doesn't look like an xpath. is there a way to select objects and copy the xpath to that object directly?

What a great tool! Thanks

you do iterateNext twice - once when you define var Authors and then again in headers = Authors.iterateNext

you'll likely want to delete .iterateNext().textContent;
from the line starting with var Authors =

FWIW - there is a newer, simpler syntax for evaluating xpaths:

ZU.xpath and ZU.xpathText

they don't work exactly the same way as doc.evaluate does, but save you a lot of messy code, see the translators above for examples.
The main difference is that you can't use ZU.xpath in a while loop, you have to use a for loop

After a few days of working on this in my free time, I feel I've hit a wall. I can use doc.evaluate to return single items correctly. I have tested multiple XPaths for all of the citation info I need, so that if I comment out existing variables I can Zotero.debug to test each XPath and see that it works. however I have 2 issues.
1) I am not able to use ZU.xpath. All of my attempts to use it have returned errors
2) I can't seem to figure out how to link together multiple pieces of bibliographic info into a working translator. I've looked at the examples above and they seem awfully different from the example ones in HWZT. Since these are for books and presentations, are there any relevant translators that are for journal articles? If I could find a translator that works and just adapt it by pointing it at the right URL and changing the XPaths for each piece of bibliographic information...well that might be cheating but it seems more in the realm of something i might be able to accomplish.

https://gist.github.com/tEXkYzqK/5759947

look at https://github.com/zotero/translators/blob/master/SciELO.js#L20 as an example for a framework journal translator

ideally, issue a pull request via github as described under A here
https://github.com/citation-style-language/styles/blob/master/CONTRIBUTING.md

substituting
https://github.com/zotero/translators
for https://github.com/citation-style-language/

if you can't make it work, putting it up as a gist will do as well, but the pull request is much preferable

I'll also add that I've tried matching anyting before the first ";" instead WITH .match( /\;$/) to no avail.

yes, that would be the correct regex to use. Are you dealing with multi-line strings (the answer is probably yes, even if the string appears as a single line on a webpage because of the way HTML is written)? If so, do you want to remove everything after ; including any additional lines? The "gm" flags are a bit confusing in regards to what you want to accomplish.

I think what you want is probably .remove(/;[\s\S]*/)
This will remove all characters (including newlines) after (and including) the ;

@aurimas
Thanks. I originally put the gm flags in there because I was sort of trying a shotgun approach. I thought perhaps the reason I was unable to remove any characters at first was because the match was stopping at the first ";"- so I put in the global flag. then I thought maybe it was a multi-line issue, so i put in the m flag. when I finally discovered the problem was a combination of syntax issues with /\;*/ (I needed to backslash out the ";" and add "*" to continue matching) I decided "if it ain't broke, don't fix it" and stopped messing with the code. In the interest of increasing my understanding, I'll play around with some of the expressions you recommended. In the end, I was able to scrape all of the bibliographic info I needed for my purposes.

When I have a spare minute, I'll clean it up a bit and add a few more fields and put it on Github. Thanks again for your help.

The translator works OK: I used it to complete the project I was working on at the time, and I haven't had an opportunity to return to it recently. I didn't post it to Github because I noticed a few things wrong with it. When searching abstracts over several years on the ASCO meeting library website, certain years fail to return formatted results. I suspect that this is because the xpath to the information is different in those years (someone re-formatted the page when they entered the data or something). I know that a small tweak in the xpath I identified for each bibliographic entry would patch this problem, but it might not work in every case.
Instead, I thought it would be good to use a multi scraper and set it up to read the section headers directly to input the info. I will try again to work on this when I have some spare time. In the meantime, I could post the translator I have just as an FYI to anyone looking for this.

I'd also like to try developing one for clinicaltrials.gov, which is a website that collects data on clinical trials in the US. These entries wouldn't be journals, books, or anything that seems to fit neatly into an existing category, so I don't really know where to start when it comes to creating a translator for something like that.

Anyway, thanks for your help. I really learned a lot and in the future if I need a site translator, I can try to jump right in.

added pull request here

https://github.com/zotero/translators/pull/601

@Graham_MTM

I came across this thread while searching for a way to get ClinicalTrials.gov data into Zotero, other than by creating a web page entry and then editing manually. You'd mentioned wanting to work on a ClinicalTrials.gov filter - is that still on your wishlist? I'd aid and abet, although I'd be starting from the bottom of the learning curve.