Pass a JavaScript Variable Value into Input Type Hidden Value

Pass a javascript variable value into input type hidden value

You could give your hidden field an id:

<input type="hidden" id="myField" value="" />

and then when you want to assign its value:

document.getElementById('myField').value = product(2, 3);

Make sure that you are performing this assignment after the DOM has been fully loaded, for example in the window.load event.

How to pass js variable into hidden form field?

Remove this <?php echo <script>demo</script> from hidden field and leave it blank.

Write followed code

var demo =1;
$('#demo_val').val(demo);

in your script.
You can get value by

var field_vemo = $('#demo_val').val();

How to assign a javascript variable to a hidden input?

You have to add the javascript after the Input Hidden element is rendered, ie order of the code arrangement is important since you have added the javascript to execute when it is rendered in browser . Make sure no other element has the same id value "id".

I prefer to use a function to execute on form submit as follows.

    <form action="myServlet" onSubmit="setVal();">
<input type="hidden" id="id" value="" name="total">
     <input type="submit" value="Go!"/>

</form>

<script>        

function setVal(){
   var a = 2;
    document.getElementById('id').value=a;
}
</script>

How to add a JS variable into a hidden form value

Try this; the description is mentioned in the code snipp ; basically
get the inner text of the span tag and assign it to the hidden input.

<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
</head>

<body>

    <p class="total-box"><span>This is the text</span></p>
    <input type="hidden" id="xyz" /> 

    <script src="https://ajax.googleapis.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
    <script>

       var totalDonation = $(".total-box>span").text();

       $("#xyz").val(totalDonation); // Sets the text from total donation to your hidden input

       var hiddeninput = $("#xyz").val();

       console.log(hiddeninput); // displays hidden input data

    </script>

</body>
</html>

Passing a js variable value in an input type hidden and then retrieve it with php

In your script you're returning before you've finished your function.

You should only use return when you want to stop the function and return a result. Anything after return will not be read.

This is what your code should look like:

<script type="text/javascript">
  var nb=0;
  function count_nb_submit() {
    nb++;
    document.getElementById('nb').value=nb;
    return nb;
  }
</script>

How to set a value to a hidden type input from javascript

If you give the hidden input an id, you can then query the DOM for that element and set the value, like so:

document.getElementById('userid').value = '123';

Insert jquery variable value into input hidden field

Inserting into hidden input field based on your code

$(document).ready(function() {    $('.pro_img').click(function() {            var imgpro = jQuery(this).attr('src');        $('#hidden_pro_image').val(imgpro);           alert($('#hidden_pro_image').val());    });});

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script><img class="pro_img" src="https://i0.wp.com/wptavern.com/wp-content/uploads/2016/07/stack-overflow.png?ssl=1" width="100px" />
<input id="hidden_pro_image" type="hidden" value="" />

Passing JavaScript variables to PHP as a hidden input

You did'nt set the form method so it defaults to GET
You should set

<form action="search" method="POST">

try

JS :

var yes = "<?php echo $_POST['yes']; ?>";
document.getElementById('yes').innerHTML = yes;

Pass a JavaScript Variable Value into Input Type Hidden Value