The best replacement for dojo is jquery.

The best alternatives to dojo are rated as following:
★★★★★  jquery
★★★  extjs
★★★  yui
★★  prototype
★★  gwt
★  backbone
★  angular
★  sencha
★  dojang
★  ext
★  ember
★  dijit
  mootools
  scriptaculous
  dwr
  requirejs
  jquery ui
  angularjs
  ext js

Your alternative for dojo is not listed? Suggest!
Speaking about dojo, one probably shouldn't forget about json.

Other search terms related to dojo and their ratings are:
★★★★★ json
You have in mind a companion for dojo and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of dojo in all years. Click on graph for more.
dojo
jquery
extjs