Check all checkboxes in a form

checking_ckeckboxes.js

$.each($('input:checkbox'), function(key, elem) {
   $(elem).attr('checked', 'checked');
});

pure_js_version.js

var inputs = document.getElementsByTagName('input');

for (var i = 0; i < inputs.length; i++) {
   if (inputs[i].type == 'checkbox') {
      inputs[i].checked = true;
   }
}