gistfile1.js

    var baseUrl = 'http://blast.ncbi.nlm.nih.gov/Blast.cgi',
  			program,
				blastPrograms;

			switch (App.blast.context)
			{
				case 'rna-sequence' :
				case 'mrna-transcript' :
					program = blastPrograms = 'tblastx';
					break;
				case 'protein-sequence' :
				case 'mrna-protein' :
					program = blastPrograms = 'blastp';
					break;
				case 'dna-sequence' :
					program = 'blastn';
					blastPrograms = 'megaBlast';
					break;
			}			

			// to specify species use 'EQ_MENU' in post
			var params = {
				'PAGE_TYPE' : 'BlastSearch',
				'SHOW_DEFAULTS' : 'on',
				'LINK_LOC' : 'blasthome',
				'PROGRAM' : program,
				'BLAST_PROGRAMS' : blastPrograms,
				'QUERY' : App.blast.query
			};

			// form is used to POST data to get around GET request character limit
			$tempForm = $('<form>').attr({
				'method' : 'post',
				'action' : baseUrl,
				'target' : '_blank'
			});

			for (var i in params) {
				if (params.hasOwnProperty(i)) {
					$('<input>').attr({
						'type' : 'hidden',
						'name' : i,
						'value' : params[i]
					}).appendTo($tempForm);
				}
			}

			$tempForm.submit().remove();