Checking if a PHP array is empty in JavaScript - php

Question

Hi I have a form where a user can enter one or more books into a DB. Whenever a user enters one book and forgets to enter the title, a JavaScript alert comes and alerts him to enter a title. Now if he has two or more books and he forgets to enter the title, the alert doesn't show up.
This is my JavaScript function.
function validateForm()
{
var a=document.forms["submit_books"]["title"].value;
if (a==null || a=="")
{
alert("Please enter a 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 a valid email address.");
return false;
}
}
And Here is my PHP code
<form method="post" name="submit_books" onsubmit="return validateForm()" action="<?php echo $_SERVER['PHP_SELF']; ?>">
<?php for ($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 even tried putting the PHP array into a JavaScript one.
<?
$js_array = json_encode($title);
echo "var title = ". $js_array . ";\n";
?>
var index = 1;
if( index < title.length)
{
alert("Please enter a Title");
return false;
}
There must be an easier way doing this

Answer 1

You should be doing
var index = 1;
if( index > title.length )
{
alert("Please enter a Title");
return false;
}
Since there is no record if title.length = 0, that is, if 1 > 0 then there is no title.
You can also check
if( title.length === 0 )

Answer 2

Try to use inside html form
<label>
<span>Book Title: (required)</span>
<input name="book" type="text" placeholder="Please enter your books title" required autofocus>
</label>
Then use javascript to validate
(function() {
// Create input element for testing
var inputs = document.createElement('input');
// Create the supports object
var supports = {};
supports.autofocus = 'autofocus' in inputs;
supports.required = 'required' in inputs;
supports.placeholder = 'placeholder' in inputs;
// Fallback for autofocus attribute
if(!supports.autofocus) {
}
// Fallback for required attribute
if(!supports.required) {
}
// Fallback for 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';
}
}
})();

Answer 3

You can do this like:
<?
echo "var title_length = ". count($title) . ";\n";
?>
var index = 1;
if( index > title_length)
{
alert("Please enter a Title");
return false;
}