How do I keep checkboxes checked after refreshing a page in HTML?

liaomerit
May 19, 2023
202 views
0 votes
2 Answers

I am studying how to keep checkboxs stay checked after refreshing the page.
And I find this helps.
However, the code, does not work right at my server. When I refresh, checkboxs stayed unchecked.
I also use this compiler. NOT GOOD.
See

The code I use:

<!DOCTYPE html>
<html>
<head>
<style type="text/css">
#checkbox-container{
  margin: 10px 5px;
}

#checkbox-container div{
  margin-bottom: 5px;
}

#checkbox-container button{
  margin-top: 5px;
}

input[type=text] {
  padding: .5em .6em;
  display: inline-block;
  border: 1px solid #ccc;
  box-shadow: inset 0 1px 3px #ddd;
  border-radius: 4px;
}
</style>
</head>

<body>
<div id="checkbox-container">
  <div>
    <label for="option1">Option 1</label>
    <input type="checkbox" id="option1">
  </div>
  <div>
    <label for="option2">Option 2</label>
    <input type="checkbox" id="option2">
  </div>
  <div>
    <label for="option3">Option 3</label>
    <input type="checkbox" id="option3">
  </div>
</div>
</body>


</html>
<script>
    var checkboxValues = JSON.parse(localStorage.getItem('checkboxValues')) || {},
    $checkboxes = $("#checkbox-container :checkbox");
    
    $checkboxes.on("change", function(){
      $checkboxes.each(function(){
        checkboxValues[this.id] = this.checked;
      });
      
      localStorage.setItem("checkboxValues", JSON.stringify(checkboxValues));
    });
    
    // On page load
    $.each(checkboxValues, function(key, value) {
      $("#" + key).prop('checked', value);
    });
</script>

It seems to me that the code only works on CODEPEN.
May somebody tells me what is wrong?
Thanks a lot.

Answers

<!DOCTYPE html>
<html>
  <head>
    <style type="text/css">
      #checkbox-container {
        margin: 10px 5px;
      }

      #checkbox-container div {
        margin-bottom: 5px;
      }

      #checkbox-container button {
        margin-top: 5px;
      }

      input[type="text"] {
        padding: 0.5em 0.6em;
        display: inline-block;
        border: 1px solid #ccc;
        box-shadow: inset 0 1px 3px #ddd;
        border-radius: 4px;
      }
    </style>
  </head>

  <body>
    <div id="checkbox-container">
      <div>
        <label for="option1">Option 1</label>
        <input type="checkbox" id="option1" />
      </div>
      <div>
        <label for="option2">Option 2</label>
        <input type="checkbox" id="option2" />
      </div>
      <div>
        <label for="option3">Option 3</label>
        <input type="checkbox" id="option3" />
      </div>
    </div>

    <script src="https://code.jquery.com/jquery-3.6.0.min.js"></script>
    <script>
      $(document).ready(function () {
        var checkboxValues =
            JSON.parse(localStorage.getItem("checkboxValues")) || {},
          $checkboxes = $("#checkbox-container :checkbox");

        $checkboxes.on("change", function () {
          $checkboxes.each(function () {
            checkboxValues[this.id] = this.checked;
          });

          localStorage.setItem(
            "checkboxValues",
            JSON.stringify(checkboxValues)
          );
        });

        // On page load
        $.each(checkboxValues, function (key, value) {
          $("#" + key).prop("checked", value);
        });
      });
    </script>
  </body>
</html>

The code you provided has a couple of issues:

The script tag is placed outside the HTML body. Move the script tag inside the body or wrap the JavaScript code in a proper script block.
The jQuery library is not included in the code. To use jQuery functions like $(), you need to include the jQuery library before using it.

Why not use a fieldset and track changes to the entire thing?

No jQuery dependency
Simplifies HTML
Only adds one listener

I’ve also genericized the listener so that it can easily be modified to handle more fieldsets as well as other input types. input type="text" support added as an example.

window.addEventListener("load", (event) => {
    restoreChanges("fieldset1");
    trackChanges("fieldset1");
});

// Reads localStorage back into fieldset's inputs 
function restoreChanges(fieldsetId) {
    var json = localStorage.getItem(fieldsetId);
    if(json) {
        JSON.parse(json).forEach(item => {
            if(typeof item.value == "boolean") {
                // Handle checkbox
                document.getElementById(item.id).checked = item.value;
            } else {
                document.getElementById(item.id).value = item.value;
            }
        });
    }
}

// Automatically saves fieldset's inputs to localStorage
function trackChanges(fieldsetId) {
    // Add listener to entire fieldset
    document.getElementById(fieldsetId).addEventListener('change', (event) => {
        var inputValues = [];
        var inputs = event.currentTarget.getElementsByTagName("input");
        Array.from(inputs).forEach(element => inputValues.push(
            {
                type: "input",
                id: element.id,
                value: element.type == "checkbox" ? element.checked : element.value
            }
        ));
        localStorage.setItem(event.currentTarget.id, JSON.stringify(inputValues));
        console.debug(inputValues);
    });
}

<!DOCTYPE html>
<html>
  <body>
    <fieldset id="fieldset1">
        <legend>Choose your options</legend>
        <input type="checkbox" id="option1" />
        <label for="option1">Option 1</label><br/>

        <input type="checkbox" id="option2" />
        <label for="option2">Option 2</label><br/>

        <input type="checkbox" id="option3" />
        <label for="option3">Option 3</label><br/>

        <label for="option4">Option 4</label>
        <input type="text" id="option4" /><br/>
    </fieldset>
  </body>
</html>

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