Generate Promo Code / Random String

function generateRandomPromo() {     length = 6;     chars = '#aA';     var mask = '';     if (chars.indexOf('a') > -1) mask += 'abcdefghijklmnopqrstuvwxyz';     if (chars.indexOf('A') > -1) mask += 'ABCDEFGHIJKLMNOPQRSTUVWXYZ';     if (chars.indexOf('#') > -1) mask += '0123456789';     if (chars.indexOf('!') > -1) mask += '~`!@#$%^&amp;*()_+-={}[]:";\'<>?,./|\\';     var result = '';     for (var i = length; i > 0; --i) result += mask[Math.round(Math.random() * (mask.length - 1))];     $('#EventPromocode_promocode').val(result); }

Validation Form

HTML

<form onsubmit="return validateQuestionForm();">

JAVASCRIPT

function validateQuestionForm(){         var flag=true;     var err=false;     var err_print = "Error :<br>";         // check titile     if($('#title').val()=="") {         err = true;         err_print += "- Please insert question title.<br>";         $('#title').css({             "border": "1px solid red",             "background": "#FFCECE"         });     } else {         $('#title').css({             "border": "",             "background": ""         });     }         // check option and checkbox which id = correct_radio_     if($('input:radio[id^="correct_radio_"]').is(":checked") || $('input:checkbox[id^="correct_radio_"]').is(":checked")) {     } else {             err = true;             err_print += "- Please select correct option.<br>";     }         // check option text box which class = correct_txt     $('input[class="correct_txt"]').each(function() {         if ($.trim($(this).val()) == '') {             err = true;             if(flag==true) {                 err_print += "- Please insert question answer.<br>";                 flag=false;             }             $(this).css({                 "border": "1px solid red",                 "background": "#FFCECE"             });                     } else {             $(this).css({                 "border": "",                 "background": ""             });         }     });         // error print     if(err==true) {         $('#error_notification').removeClass('displaynone').html(err_print);         return false;     } else {         return true;     } }   // type change radio to checkbox || checkbox to radio function changeAnswerType(current_type,change_type,answer_type){         $('#typechange').find('input:'+current_type).attr('type',change_type,'checked','');     if(answer_type=='single') {         $('#addmore').attr('onclick','htmlChange("single","second")');     }else {         $('#addmore').attr('onclick','htmlChange("multiple","second")');     }   }