Check All - Uncheck All multiple checkboxes using jquery

Sometimes later, i had to check and/or uncheck multiple checkboxes having same name being displayed dynamically). I have one checkbox for Check/Uncheck All, and depending on that, i had to check or uncheck other checkboxes. And if any one of the checkboxes, besides main checkbox, was checked or unchecked, then i would have to check or uncheck the main checkbox as well.
The text i have writte here might seem little confusing than the original source code, but the main point is i had to check/uncheck multiple checkboxes at once. So here is the jquery code that i wrote for doing the same.

$(document).ready(function() {
   //get count of checkboxes with the same name
   var countBoxes = $("input[name='chkTest[]']").size();
   //move through each checkbox
   $("input[name='chkTest[]']").each(function() {
      $(this).click(function() { 
         //get the state, checked or not, i.e. true or false
  var state = $(this).attr("checked");
  //get the length of checked checkboxes
  var chkedLength = $("input[name='chkTest[]']:checked").length;
  //make the checked or unchecked state
  var chkAllState = (chkedLength == countBoxes) ? true : false;
  //now apply the state to main checkbox
 $("input[name='chkAll']").attr("checked", chkAllState);
      });
   });
   //this code checks or unchecks all sub-checkboxes depending on checked state
   $("input[name='chkAll']").click(function() {
      var chkAllStatus = $(this).attr('checked');
      $("input[name='chkTest[]']").attr("checked", chkAllStatus);
   });
});