Pandoc markdown BibTex key export from Zotero Firefox add-on, as described in the [forum](https://forums.zotero.org/discussion/30875/bibtex-key-translator-for-markdown-pandoc/) entry.

BibTexCiteKeyForMarkdown.js

{
  "translatorID": "7cb70025-a888-4a29-a210-93ec52da40d5",
  "translatorType": 3,
	"label": "BibTeX key for Markdown",
	"creator": "created by liob based on the works of Peter O'Brien, Simon Kornblith and Richard Karnesky",
	"target": "bib",
	"minVersion": "2.1.9",
	"maxVersion": null,
	"priority": 200,
	"inRepository": true,
	"browserSupport": "gcsv",
	"displayOptions": {
		"exportCharset": "UTF-8",
		"exportNotes": false,
		"exportFileData": false
	},
	"lastUpdated": "2013-07-16 17:00:00"
}



//%a = first author surname
//%y = year
//%t = first word of title
var citeKeyFormat = "%a_%t_%y";



var zotero2bibtexTypeMap = {
	"book":"book",
	"bookSection":"incollection",
	"journalArticle":"article",
	"magazineArticle":"article",
	"newspaperArticle":"article",
	"thesis":"phdthesis",
	"letter":"misc",
	"manuscript":"unpublished",
	"interview":"misc",
	"film":"misc",
	"artwork":"misc",
	"webpage":"misc",
	"conferencePaper":"inproceedings",
	"report":"techreport"
};


/*
 * three-letter month abbreviations. i assume these are the same ones that the
 * docs say are defined in some appendix of the LaTeX book. (i don't have the
 * LaTeX book.)
 */
var months = ["jan", "feb", "mar", "apr", "may", "jun",
			  "jul", "aug", "sep", "oct", "nov", "dec"];

/*
 * new mapping table based on that from Matthias Steffens,
 * then enhanced with some fields generated from the unicode table.
 */



var alwaysMap = {
	"|":"{\\textbar}",
	"<":"{\\textless}",
	">":"{\\textgreater}",
	"~":"{\\textasciitilde}",
	"^":"{\\textasciicircum}",
	"\\":"{\\textbackslash}"
};

var strings = {};
var keyRe = /[a-zA-Z0-9\-]/;
var keywordSplitOnSpace = true;
var keywordDelimRe = ',\\s*';
var keywordDelimReFlags = '';

function setKeywordSplitOnSpace( val ) {
	keywordSplitOnSpace = val;
}










function mapEscape(character) {
	return alwaysMap[character];
}

function mapAccent(character) {
	return (mappingTable[character] ? mappingTable[character] : "?");
}

// a little substitution function for BibTeX keys, where we don't want LaTeX 
// escaping, but we do want to preserve the base characters

function tidyAccents(s) {
	var r=s.toLowerCase();

	// XXX Remove conditional when we drop Zotero 2.1.x support
	// This is supported in Zotero 3.0 and higher
	if (ZU.removeDiacritics !== undefined)
		r = ZU.removeDiacritics(r, true);
	else {
	// We fall back on the replacement list we used previously
		r = r.replace(new RegExp("[ä]", 'g'),"ae");
		r = r.replace(new RegExp("[ö]", 'g'),"oe");
		r = r.replace(new RegExp("[ü]", 'g'),"ue");
		r = r.replace(new RegExp("[àáâãå]", 'g'),"a");
		r = r.replace(new RegExp("æ", 'g'),"ae");
		r = r.replace(new RegExp("ç", 'g'),"c");
		r = r.replace(new RegExp("[èéêë]", 'g'),"e");
		r = r.replace(new RegExp("[ìíîï]", 'g'),"i");
		r = r.replace(new RegExp("ñ", 'g'),"n");                            
		r = r.replace(new RegExp("[òóôõ]", 'g'),"o");
		r = r.replace(new RegExp("œ", 'g'),"oe");
		r = r.replace(new RegExp("[ùúû]", 'g'),"u");
		r = r.replace(new RegExp("[ýÿ]", 'g'),"y");
	}

	return r;
};

var numberRe = /^[0-9]+/;
// Below is a list of words that should not appear as part of the citation key
// in includes the indefinite articles of English, German, French and Spanish, as well as a small set of English prepositions whose 
// force is more grammatical than lexical, i.e. which are likely to strike many as 'insignificant'.
// The assumption is that most who want a title word in their key would prefer the first word of significance.
var citeKeyTitleBannedRe = /\b(a|an|the|some|from|on|in|to|of|do|with|der|die|das|ein|eine|einer|eines|einem|einen|un|une|la|le|l\'|el|las|los|al|uno|una|unos|unas|de|des|del|d\')(\s+|\b)/g;
var citeKeyConversionsRe = /%([a-zA-Z])/;
var citeKeyCleanRe = /[^a-z0-9\!\$\&\*\+\-\.\/\:\;\<\>\?\[\]\^\_\`\|]+/g;

var citeKeyConversions = {
	"a":function (flags, item) {
		if(item.creators && item.creators[0] && item.creators[0].lastName) {
			return item.creators[0].lastName.toLowerCase().replace(/ /g,"_").replace(/,/g,"");
		}
		return "";
	},
	"t":function (flags, item) {
		if (item["title"]) {
			return item["title"].toLowerCase().replace(citeKeyTitleBannedRe, "").split(/\s+/g)[0];
		}
		return "";
	},
	"y":function (flags, item) {
		if(item.date) {
			var date = Zotero.Utilities.strToDate(item.date);
			if(date.year && numberRe.test(date.year)) {
				return date.year;
			}
		}
		return "????";
	}
}


function buildCiteKey (item,citekeys) {
	var basekey = "";
	var counter = 0;
	citeKeyFormatRemaining = citeKeyFormat;
	while (citeKeyConversionsRe.test(citeKeyFormatRemaining)) {
		if (counter > 100) {
			Zotero.debug("Pathological BibTeX format: " + citeKeyFormat);
			break;
		}
		var m = citeKeyFormatRemaining.match(citeKeyConversionsRe);
		if (m.index > 0) {
			//add data before the conversion match to basekey
			basekey = basekey + citeKeyFormatRemaining.substr(0, m.index);
		}
		var flags = ""; // for now
		var f = citeKeyConversions[m[1]];
		if (typeof(f) == "function") {
			var value = f(flags, item);
			Zotero.debug("Got value " + value + " for %" + m[1]);
			//add conversion to basekey
			basekey = basekey + value;
		}
		citeKeyFormatRemaining = citeKeyFormatRemaining.substr(m.index + m.length);
		counter++;
	}
	if (citeKeyFormatRemaining.length > 0) {
		basekey = basekey + citeKeyFormatRemaining;
	}

	// for now, remove any characters not explicitly known to be allowed;
	// we might want to allow UTF-8 citation keys in the future, depending
	// on implementation support.
	//
	// no matter what, we want to make sure we exclude
	// " # % ' ( ) , = { } ~ and backslash
	// however, we want to keep the base characters 

	basekey = tidyAccents(basekey);
	basekey = basekey.replace(citeKeyCleanRe, "");
	var citekey = basekey;
	var i = 0;
	while(citekeys[citekey]) {
		i++;
		citekey = basekey + "-" + i;
	}
	citekeys[citekey] = true;
	return citekey;
}

function doExport() {
	//Zotero.write("% BibTeX export generated by Zotero "+Zotero.Utilities.getVersion());
	// to make sure the BOM gets ignored
		
	var first = true;
	var citekeys = new Object();
	var item;
	while(item = Zotero.nextItem()) {
		// determine type
		var type = zotero2bibtexTypeMap[item.itemType];
		if (typeof(type) == "function") { type = type(item); }
		if(!type) type = "misc";
		
		// create a unique citation key
		var citekey = buildCiteKey(item, citekeys);
		
		// write citation key
		Zotero.write((first ? "" : "; ") + "@" + citekey);
		first = false;
		
	}
	
}