How do I keep single checkbox stay checked after refreshing the page?

Question

HTML code:

    <div class="wrap">
        <h3>Background Swap:</h3>
        <form action="" method="POST">
            <div id="checkbox-container">
                Shadowless background: <input type="checkbox" name="new_background" id="checker" <?php echo (isset($_POST['new_background']))? "checked='checked'": "";?>/><br /><br />
            </div>
            <input type="submit" name="submit" value="Upgrade Background" class="button" />
        </form>
    </div>

This will make the checkbox stays checked, but when page is refresh or exit and comes back, the checkbox will be unchecked. Therefore, after some research, I tried the localStorage, but doesn't seem to quite figure it out yet.

localStorage code:

    var checkboxValue = JSON.parse(localStorage.getItem('checkboxValue')) || {};
    var $checkbox = $("#checkbox-container :checkbox");

    $checkbox.on("change", function(){
        $checkbox.each(function(){
            checkboxValue[this.id] = this.checked; 
        });
        localStorage.setItem("checkboxValue", JSON.stringify(checkboxValue));
    });

    //on page load
    $.each(checkboxValue, function(key, value){
        $("#" + key).prop('checked', value);
    });

I have script tags around the localStorage code and after implementing these codes, my checkbox still doesn't stays checked.

Both code as a whole:

<div class="wrap">
<h3>Background Swap:</h3>
<form action="" method="POST">
    <div id="checkbox-container">
        Background Swap: <input type="checkbox" name="new_background"/>
    </div>
    <script>
        var checkboxValue = JSON.parse(localStorage.getItem('checkboxValue')) || {}
        var $checkbox = $("#checkbox-container :checkbox");

        $checkbox.on("change", function(){
            $checkbox.each(function(){
                checkboxValue[this.id] = this.checked; 
            });
            localStorage.setItem("checkboxValue", JSON.stringify(checkboxValue));
        });

        //on page load
        $.each(checkboxValue, function(key, value){
            $("#" + key).prop('checked', value);
        });
        </script>
        <input type="submit" name="submit" value="Upgrade Background" class="button"/>
</form>
</div>

I would like to thank everyone that took time to help me figure out the solution to my question with the biggest thanks to @Pranav C Balan!!! Check out the finished code @ http://stackoverflow.com/a/44321072/3037257

Answer 1

I think your code is executing before the form elements are loading, so place it at the end of your code or wrap it using document ready handler to execute only after the elements are loaded. If you were placed the code before the element $("#checkbox-container :checkbox") would select nothing since it is not yet loaded in the DOM.

One more thing to do, in your code the checkbox doesn't have any id so add a unique id to the element to make it work since the JSON is generating using the id value.

<div class="wrap">
  <h3>Background Swap:</h3>
  <form action="" method="POST">
    <div id="checkbox-container">
      Background Swap: <input type="checkbox" id="name" name="new_background" />
    </div>

    <input type="submit" name="submit" value="Upgrade Background" class="button" />
  </form>
  <script>
    var checkboxValue = JSON.parse(localStorage.getItem('checkboxValue')) || {}
    var $checkbox = $("#checkbox-container :checkbox");

    $checkbox.on("change", function() {
      $checkbox.each(function() {
        checkboxValue[this.id] = this.checked;
      });
      localStorage.setItem("checkboxValue", JSON.stringify(checkboxValue));
    });

    //on page load
    $.each(checkboxValue, function(key, value) {
      $("#" + key).prop('checked', value);
    });
  </script>
</div>

Working demo : FIDDLE

---

<script>
  // document ready handler
  // or $(document).ready(Function(){...
  jQuery(function($) {
    var checkboxValue = JSON.parse(localStorage.getItem('checkboxValue')) || {}
    var $checkbox = $("#checkbox-container :checkbox");

    $checkbox.on("change", function() {
      $checkbox.each(function() {
        checkboxValue[this.id] = this.checked;
      });
      localStorage.setItem("checkboxValue", JSON.stringify(checkboxValue));
    });

    //on page load
    $.each(checkboxValue, function(key, value) {
      $("#" + key).prop('checked', value);
    });
  });
</script>
<div class="wrap">
  <h3>Background Swap:</h3>
  <form action="" method="POST">
    <div id="checkbox-container">
      Background Swap: <input type="checkbox" id="name" name="new_background" />
    </div>

    <input type="submit" name="submit" value="Upgrade Background" class="button" />
  </form>

</div>

Working demo : FIDDLE