Passing JavaScript variables to PHP as a hidden input

You have to set the value property of the <input>, not the innerHTML. You also need to give the <input> a different name than other fields or the "submit" button. Finally, you have to give your <input> an "id" property so that you can actually get it with getElementById().

You should be setting the value of the hidden input, not the innerHTML. This code should work:

function pass() {
   //some code
   document.getElementById('yes').value = yes; //where yes is a var
}

Another problem, as noted by Pointy, is that the hidden input doesn't actually have an id, so you should give it an id (in this case the id should be yes).

Something you should also do is escape the html you are inserting into the hidden input with PHP, so it doesn't accidentally get parsed. You can do this with htmlspecialchars():

<form action="search">
        <input type="hidden" id="yes" name="yes" value="<?php $yes= htmlspecialchars("<p id='yes'> </p>"); echo $yes;?>" />
        <input type="submit" value="Done" />
</form>

• Your submit button and your hidden field have the same name yes .

• You try to access your hidden input by id yes , and your input does not have this id , use getElementByName('yes') instead or give your hidden field id='yes'.

• You use innerHtml which only sets or returns the inner HTML of an element,it should be value.

HTML CODE:

<form action="search">
    <input id='yes' type="hidden" name="yes" value="<?php $yes= "<p id='yes'> </p>"; echo $yes;?>" />
    <input type="submit" name="yess" value="Done" />
</form>

JS :

document.getElementById('yes').value = yes;//yes is a variable