We have two pieces of evidence that JQuery is on the up. One survey suggests it is used by half of all websites; another has the information that it is used by 74%  of mobile web developers.

The title of a blog post on W3techs.com tells the story in a single line:

jQuery now runs on every second website.

Matthias Gelbmann goes on to report that:

In the last year, every 4 minutes one of the top 1 million sites started to use jQuery.

This graph shows the increase in usage from 25% of website in October 2010 to just over 50% this month:

Mozilla's recent survey of mobile web developers investigated jQuery from the other side of the fence and found it to be easily the most popular library among the 590 developers who  filled in its online questionnaire.

While there was a lot of feedback was that developers don’t like libraries and use their own hand-rolled solutions on mobile instead, the survey collected 66 libraries in total, some of them used by only 1 or 2 developers.

The entire list in order of popularity was:

jQuery, jQuery mobile, Zepto.js, Sencha Touch, JQTouch, XUI.js, Backbone, Mootools mobile, Lime.js, Sproutcore, Angular JS, Underscore, Bootstrap , Enyo, Modernizr, Dojo, handlebars, JO, Closure, Dojo Toolkit, GWT, Hammer.js, iScroll, require.js, YUI, Chibi, Ember.js, Kendo, Kinetic, Lungo.js, Nimblekit, Prototype, Wink, Adobe Air, Atto, Box2D, ChesterGL, Cobra, Crafty, Cujo, d3.js, Dart , Dojo Mobile, Dojo Mini, enhance.js, Eyebrow.js, fitml, gl-matrix, H5BP, JQMobi, Javelin, Jukebox, Knockout, MProject, Mootools, Openlayers, Path , Playcanvas, pointer.js, Raphael, Sugar.js, TerrificJS, Thorax, Titanium Mobile, Uxebu bikeshed, Wakanda

As this summary graph shows, five libraries were selected by at least 5% of the respondents and JQuery was way ahead, being used to build mobile web apps/sites by 74%, with jQuery used by 51%. Zepto.js in third place trails a long way behind with 20%, Sencha touch was nominated by 15% and JQT Touch by 10%. More than one checkbox could be selected so the percentages add up to more than 100%:

Of course none of this means that jQuery is the best library but there is a lot of sense in choosing a library that is most popular. It is more likely to survive and develop and there are going to be a lot of other people who know how to use it and have encountered and reported the bugs that you are about to meet. It seems that jQuery is some sort of winner and being a winner makes it more so.