HTML PHP input checked attribute on checkbox without submitting form

Question

I have a website, and on it I have a form with check-boxes to be filled. In PHP, I am wondering if there is a checked attribute which works when focus is lost on the check-box, not when the submit button us clicked. I have tried

    if (isset($_POST['check1'])) {

    // Checkbox is selected
    } else {

   // Alternate code
   }   

but it only works when the submit button is clicked. Is there any other way to do this?

Answer 1

Since PHP is a server-side script (https://en.wikipedia.org/wiki/Server-side_scripting), there's no way to instantiate code on a client-side (https://en.wikipedia.org/wiki/Client-side_scripting) event (such as loss of focus). To check if the checkbox is checked BEFORE the form is submitted, you will need to run a javascript/JQuery script.

For instance, you could use AJAX with JQuery to trigger the event.

$(function(){ 
    $('.checkbox').focusout(function(){ 
        $.ajax({ 
            ... 
        }); 
    }); 
}); 

Then you would have the $.ajax(); function point to a PHP script to execute whatever you need done.

You can find more here:

1. $.ajax(): http://api.jquery.com/jquery.ajax/
2. focusout(): https://api.jquery.com/focusout/

Answer 2

You can easily achieve this with use of ajax. Fire a function when user interact

<input type='checkbox' onblur='checkbox()' />

function checkbox(){
    var xhttp = new XMLHttpRequest();
      xhttp.onreadystatechange = function() {
        if (xhttp.readyState == 4 && xhttp.status == 200) {
            console.log(xhttp.responseText);
        }
      };
      xhttp.open("GET", "checkbox.php", true);
      xhttp.send();
    }

Using onblur wont give you the desired results try changing it to different events see which matches your need

Here is the list of all events in HTML DOM EVENT