Better solution:

<script>!window.jQuery && document.write(unescape('%3Cscript src="js/minified/jquery-1.9.1.min.js"%3E%3C/script%3E'))</script>

if (!window.jQuery || typeof(jQuery) === 'undefined') {
  var jq = document.createElement('script'); jq.type = 'text/javascript';
  // Path to jquery.js file, eg. Google hosted version
  jq.src = '//ajax.googleapis.com/ajax/libs/jquery/1.10.2/jquery.min.js';
  document.getElementsByTagName('head')[0].appendChild(jq);
}

window.onload = function(){
	$(document).ready(function(){

	});
}