Checking if a PHP array is empty in JavaScript -

hi have form user can enter 1 or more books db. whenever user enters 1 book , forgets enter title, javascript alert comes , alerts him enter title. if has 2 or more books , forgets enter title, alert doesn't show up.

this javascript function.

function validateform()  {   var a=document.forms["submit_books"]["title"].value;    if (a==null || a=="")      {      alert("please enter title");      return false;      }    var status = false;       var emailregex = /^[a-z0-9._%+-]+@[a-z0-9.-]+\.[a-z]{2,4}$/i;       if (document.submit_books.email.value.search(emailregex) == -1) {            alert("please enter valid email address.");            return false;       } } 

and here php code

<form method="post" name="submit_books" onsubmit="return validateform()" action="<?php echo $_server['php_self']; ?>">                 <?php ($i=1; $i<$num_of_books + 1; $i++){                     echo "<strong>book # $i</strong><br><br>";                     ?>                       <label for="title">*title</label>: <input type="text" id="title" size="60" name="title[]" autocomplete="off"/><br><br>                <?php }?> <input type="submit" name="submit" value="submit books"> </form> 

i tried putting php array javascript one.

     <? $js_array = json_encode($title); echo "var title = ". $js_array . ";\n"; ?> var index = 1; if( index < title.length) {     alert("please enter title");      return false;  }  

there must easier way doing this

try use inside html form

<label>  <span>book title: (required)</span>  <input name="book" type="text" placeholder="please enter books title" required autofocus>  </label> 

then use javascript validate

(function() {      // create input element testing     var inputs = document.createelement('input');      // create supports object     var supports = {};      supports.autofocus   = 'autofocus' in inputs;     supports.required    = 'required' in inputs;     supports.placeholder = 'placeholder' in inputs;      // fallback autofocus attribute     if(!supports.autofocus) {      }      // fallback required attribute     if(!supports.required) {      }      // fallback placeholder attribute     if(!supports.placeholder) {      }      // change text inside send button on submit     var send = document.getelementbyid('submit');     if(send) {         send.onclick = function () {             this.innerhtml = '...processing';         }     }  })();