seeing as projectid
is an invalid element attribute, I'd say there's no right way to select on it. You'd be better off in HTML5 using
<span class="descriptionLink" data-projectid="14182">
and selecting off of $('[data-projectid="14182"]')
Or, alternatively, using classes:
<span class="descriptionLink projectid-14182">
Selecting like so:
var project_id_to_find = 14182;
$(".projectid-" + project_id_to_find);