title: JQuery code works in IE and Chrome but not Firefox
body: <p>I have written this code (i'm new to jquery) and it refuses to work in chrome.  I first manipulated it in jsfiddle then added it to the js code.</p>
  
  <p>When I used firebug I get the following error:
  Warning: Use of attributes' specified attribute is deprecated. It always returns true.
  Source File: <a href="http://ajax.googleapis.com/ajax/libs/jquery/1.8.2/jquery.min.js" rel="nofollow">http://ajax.googleapis.com/ajax/libs/jquery/1.8.2/jquery.min.js</a></p>
  
  <p>It runs ok up until the click functions.  </p>
  
  <p>Basically what I am trying to achieve is to disable certain checkboxes when other checkboxes are checked (When safety is checked, then intro is enabled, when intro is clicked both advanced are enabled).  </p>
  
  <p>So here is the Jquery code that is faulty:</p>
  
  <pre class="lang-js prettyprint-override"><code>    $(document).ready(function() {
  
      $(".safetyARC").click(function() {
      $(".advancedARC1, .advancedARC2, .advancedGAS1, .advancedGAS2, .advancedMIG1,
      .advancedMIG2, .introGAS, .introMIG").attr("disabled", true);
      $("#Notification").text("*You must enrol on the INTRO course before selecting the    
      ADVANCED");
      });
  
  
  
  
      $(".safetyGAS").click(function() {
      $(".advancedGAS1, .advancedGAS2, .advancedARC1 .advancedARC2, .advancedMIG1,
      .advancedMIG2, .introARC, .introMIG ").attr("disabled", true);
      $("#Notification").text("*You must enrol on the INTRO course before selecting the 
      ADVANCED");
      });
  
      $(".safetyMIG").click(function() {
      $(".advancedGAS1, .advancedGAS2, .advancedARC1,.advancedARC2, .advancedMIG1,  
      .advancedMIG2, .introARC, .introGAS  ").attr("disabled", true);
      $("#Notification").text("*You must enrol on the INTRO course before selecting the
      ADVANCED");
      });
  
  
      $(".introARC").click(function() {
      $(".advancedGAS1, .advancedGAS2, advancedMIG1, .advancedMIG2, .introGAS, 
      .introMIG").attr("disabled", true);
      $("#Notification").text("*Now you may chose from the ADVANCED courses");
      });
  
      $(".introGAS").click(function() {
      $(".advancedARC1, .advancedARC2, .advancedMIG1, .advancedMIG2, .introARC, 
      .introMIG").attr("disabled", true);
      $("#Notification").text("*Now you may chose from the ADVANCED courses");
      });
  
      $(".introMIG").click(function() {
      $(".advancedGAS1, .advancedGAS2, .advancedARC1, .advancedARC2, .introGAS, .introARC
      ").attr("disabled", true);
          $("#Notification").text("*Now you may chose from the ADVANCED courses");
      });
      });
  </code></pre>
  
  <p>and the HTML:</p>
  
  
  
  <pre class="lang-html prettyprint-override"><code>&lt;div id="wrapper"&gt;
      &lt;div id="header-wrapper"&gt;
          &lt;div id="header" class="container"&gt;
              &lt;div id="logo"&gt;
                  &lt;h1&gt;WeldingCourses&lt;/h1&gt;
              &lt;/div&gt;
  
          &lt;/div&gt;
          &lt;div id="banner"&gt;
              &lt;div class="content"&gt;
  
  &lt;div id="white"&gt;
  
  &lt;form name="myform" action="enrole.php" method="get" &gt;
  &lt;div id="mainForm"&gt;
  
  &lt;h3&gt;Have you had any welding experience?&lt;/h3&gt;
  &lt;input type="radio" name="experience" id="radioYes"value="yes"&gt;Yes&lt;br&gt;
  &lt;input type="radio" name="experience" id="radioNo" value="no"&gt;No
  
  
  
  &lt;div id="weldingCourse"&gt;
  
      &lt;div id="section1"&gt;
          &lt;h3&gt;Please select a Welding course and a Module?&lt;/h3&gt;
          &lt;select id="typeWeld"&gt;
           &lt;option&gt;Please Select...&lt;/option&gt;
              &lt;option id= "section2" value="1"&gt;ARC&lt;/option&gt;
              &lt;option id="section3" value="2"&gt;GAS&lt;/option&gt;
              &lt;option id="section4"value="3"&gt;MIG&lt;/option&gt;
               &lt;option id="section5"value="4"&gt;ANY&lt;/option&gt;
          &lt;/select&gt;
      &lt;/div&gt;
  
  &lt;span id="Notification"&gt;&lt;/span&gt;
  
  
     &lt;div id="div4"&gt;     
      &lt;div id="div1"&gt;
       &lt;table id="arc"&gt;
   &lt;tr class="odd"&gt;
   &lt;td&gt;CODE&lt;/td&gt;
   &lt;td&gt;TYPE&lt;/td&gt;
    &lt;td&gt;LEVEL&lt;/td&gt;
   &lt;td&gt;DESCRIPTION&lt;/td&gt;
    &lt;td&gt;SELECT&lt;/td&gt;
   &lt;/tr&gt;
   &lt;tr&gt;
   &lt;td&gt;AS&lt;/td&gt;
   &lt;td&gt;ARC&lt;/td&gt;
    &lt;td&gt;Safety&lt;/td&gt;
   &lt;td&gt;ARC Welding Saftey&lt;/td&gt;
     &lt;td&gt;&lt;input id="saftey" type="checkbox"  class="safetyARC"&gt;&lt;/td&gt;
  
  
   &lt;/tr&gt;
   &lt;tr&gt;
   &lt;td&gt;A1&lt;/td&gt;
   &lt;td&gt;ARC&lt;/td&gt;
    &lt;td&gt;Intro&lt;/td&gt;
   &lt;td&gt;Bead control and simple butt welds in mild steel.&lt;/td&gt;
   &lt;td&gt;&lt;input type="checkbox"  id="intro" class="introARC" &gt;&lt;/td&gt;
  
  
   &lt;/tr&gt;
   &lt;tr&gt;
   &lt;td&gt;A2&lt;/td&gt;
   &lt;td&gt;ARC&lt;/td&gt;
    &lt;td&gt;Advanced&lt;/td&gt;
   &lt;td&gt;Vertical Welding&lt;/td&gt;
    &lt;td&gt;&lt;input type="checkbox" class="advancedARC1"&gt;&lt;/td&gt;
   &lt;/tr&gt;
   &lt;tr&gt;
   &lt;td&gt;A3&lt;/td&gt;
   &lt;td&gt;ARC&lt;/td&gt;
    &lt;td&gt;Advanced&lt;/td&gt;
   &lt;td&gt;Specialised Electrodes&lt;/td&gt;
    &lt;td&gt;&lt;input type="checkbox" class="advancedARC2"&gt;&lt;/td&gt;
   &lt;/tr&gt;
   &lt;/table&gt;
      &lt;/div&gt;
      &lt;div id="div2"&gt;
          &lt;table id="gas"&gt;
    &lt;tr class="odd"&gt;
   &lt;td&gt;CODE&lt;/td&gt;
   &lt;td&gt;TYPE&lt;/td&gt;
    &lt;td&gt;LEVEL&lt;/td&gt;
   &lt;td&gt;DESCRIPTION&lt;/td&gt;
     &lt;td&gt;SELECT&lt;/td&gt;
   &lt;/tr&gt;
   &lt;tr&gt;
   &lt;td&gt;GS&lt;/td&gt;
   &lt;td&gt;GAS&lt;/td&gt;
    &lt;td&gt;Safety&lt;/td&gt;
   &lt;td&gt;The safe use of oxyacetylene welding equipment&lt;/td&gt;
       &lt;td&gt;&lt;input id="saftey" type="checkbox" class="safetyGAS"&gt;&lt;/td&gt;
  
   &lt;/tr&gt;
   &lt;tr&gt;
   &lt;td&gt;G1&lt;/td&gt;
   &lt;td&gt;GAS&lt;/td&gt;
    &lt;td&gt;Intro&lt;/td&gt;
   &lt;td&gt;Bead control and simple butt welds in mild steel.&lt;/td&gt;
    &lt;td&gt;&lt;input type="checkbox" id="intro" class="introGAS"&gt;&lt;/td&gt;
  
   &lt;/tr&gt;
   &lt;tr&gt;
   &lt;td&gt;G2&lt;/td&gt;
   &lt;td&gt;GAS&lt;/td&gt;
    &lt;td&gt;Advanced&lt;/td&gt;
   &lt;td&gt;Positional welds and weld testing&lt;/td&gt;
    &lt;td&gt;&lt;input type="checkbox" class="advancedGAS1"&gt;&lt;/td&gt;
   &lt;/tr&gt;
   &lt;tr&gt;
   &lt;td&gt;G3&lt;/td&gt;
   &lt;td&gt;GAS&lt;/td&gt;
   &lt;td&gt;Advanced&lt;/td&gt;
   &lt;td&gt;Gas welding of aluminium&lt;/td&gt;
    &lt;td&gt;&lt;input type="checkbox" class="advancedGAS2"&gt;&lt;/td&gt;
   &lt;/tr&gt;
  
   &lt;/table&gt;
      &lt;/div&gt;
      &lt;div id="div3"&gt;
         &lt;table id="mig"&gt;
    &lt;tr  class="odd"&gt;
   &lt;td&gt;CODE&lt;/td&gt;
   &lt;td&gt;TYPE&lt;/td&gt;
    &lt;td&gt;LEVEL&lt;/td&gt;
   &lt;td&gt;DESCRIPTION&lt;/td&gt;
     &lt;td&gt;SELECT&lt;/td&gt;
   &lt;/tr&gt;
   &lt;tr&gt;
   &lt;td&gt;MS&lt;/td&gt;
   &lt;td&gt;MIG&lt;/td&gt;
    &lt;td&gt;Safety&lt;/td&gt;
   &lt;td&gt;The safe use of MIG welding equipment&lt;/td&gt;
       &lt;td&gt;&lt;input id="saftey" type="checkbox" class="safetyMIG" value="safety"&gt;&lt;/td&gt;
  
   &lt;/tr&gt;
   &lt;tr&gt;
   &lt;td&gt;M1&lt;/td&gt;
   &lt;td&gt;MIG&lt;/td&gt;
    &lt;td&gt;Intro&lt;/td&gt;
   &lt;td&gt;Bead control and simple horizontal welds of mild steel&lt;/td&gt;
    &lt;td&gt;&lt;input type="checkbox" id="intro" class="introMIG"&gt;&lt;/td&gt;
  
   &lt;/tr&gt;
   &lt;tr&gt;
   &lt;td&gt;M2&lt;/td&gt;
   &lt;td&gt;MIG&lt;/td&gt;
    &lt;td&gt;Advanced&lt;/td&gt;
   &lt;td&gt;MIG auto-mobile body welding&lt;/td&gt;
    &lt;td&gt;&lt;input type="checkbox" class="advancedMIG1"&gt;&lt;/td&gt;
   &lt;/tr&gt;
   &lt;td&gt;M3&lt;/td&gt;
   &lt;td&gt;MIG&lt;/td&gt;
   &lt;td&gt;Advanced&lt;/td&gt;
   &lt;td&gt;MIG welding aluminium and stainless steel&lt;/td&gt;
    &lt;td&gt;&lt;input type="checkbox" class="advancedMIG2"&gt;&lt;/td&gt;
   &lt;/tr&gt;
   &lt;/table&gt;
      &lt;/div&gt;
      &lt;/div&gt;
      &lt;/div&gt;
  
       &lt;input type="submit" value="Submit"&gt;
      &lt;/form&gt;
              &lt;/div&gt;
              &lt;/div&gt;
  </code></pre>
  
  <p>Thanks in advance to anyone that answers.</p>