Conditionally Load jQuery

conditionally-load-jquery.js

// Conditionally Load jQuery (javascript)
// Source: https://gist.github.com/gists/902090/
var init, maybeLoadJq;

init = function() {
  jQuery(document).ready(function() {
    alert('Your Code Here');
  });
};

maybeLoadJq = function() {
  var jQ;
  if (!(typeof jQuery !== "undefined" && jQuery !== null)) {
    jQ = document.createElement('script');
    jQ.type = 'text/javascript';
    jQ.onload = jQ.onreadystatechange = init;
    jQ.src = '//ajax.googleapis.com/ajax/libs/jquery/1/jquery.min.js';
    return document.body.appendChild(jQ);
  } else {
    return init();
  }
};

if (window.addEventListener) {
  window.addEventListener('load', maybeLoadJq, false);
} else if (window.attachEvent) {
  window.attachEvent('onload', maybeLoadJq);
}

inject.coffee

#Conditionally load jQuery (Coffeescript)
#Source: https://gist.github.com/gists/902090/
#Inspired by: http://bit.ly/cFPMER

#function to fire once jQuery is loaded
init = ->
  jQuery(document).ready ->
    alert( 'Your Code Here')
    
#conditionally load jQuery
maybeLoadJq = ->
  if !jQuery? 
    jQ = document.createElement 'script'
    jQ.type = 'text/javascript'
    jQ.onload = jQ.onreadystatechange = init
    jQ.src = '//ajax.googleapis.com/ajax/libs/jquery/1/jquery.min.js';
    document.body.appendChild(jQ);
  else 
    init()
  
# Source: http://bit.ly/TWwg2z

if window.addEventListener #W3C
  window.addEventListener 'load', maybeLoadJq, false 
  
else if window.attachEvent #IE
  window.attachEvent 'onload', maybeLoadJq