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Editorial Team
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Asked: 2026-06-16T10:30:57+00:00

I am new to javascript and I am trying to add a conditional field

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I am new to javascript and I am trying to add a conditional field to a form. I have looked at these posts:

How do you create a hidden div that doesn't create a line break or horizontal space??
conditional display of html element forms

I have come up with this little example so far which works fine.

<html>
   <head>
       <script language="javascript">

           function cucu(form){
                   if(form.check.checked){
                   document.getElementById("cucu").style.visibility="visible"; 
                   }
                   else{
                          document.getElementById("cucu").style.visibility="hidden";
                  }
          }

              function load()
              {
                      document.getElementById("cucu").style.visibility="hidden";
              }

      </script>
  </head>

  <body onload="load()">
  <form id="form">
      <input type="checkbox" name="check" onclick="cucu(this.form)" >

      <div id="cucu">
      CUCU
      </div>

      </form>
  </body>
<html>

I have tried the same method on a larger side and the only change is that the hidden element is a text field but it just doesnt’ work.

This is the part of the form:

Album:  <INPUT TYPE="checkbox" NAME="checkAlbum" onclick="checkAlbum(this.form)" id="idAlbum">

        <div id="divAlbum" >
        Choisir un album : <input type="text" name="Album" list="Albums">
                <datalist id="Albums">

                    <?php
                        $requete = 'SELECT DISTINCT titreAlbum FROM Album';
                        $resultat = mysqli_query($connexion, $requete);
                            while($row = mysqli_fetch_assoc($resultat)){
                                echo '<option value="'.$row['titreAlbum'].'">';
                        }
                     ?>

                </datalist> <br><br>
        </div>

My head looks as follows:

<!DOCTYPE html>
<head>
    <meta http-equiv="Content-Type" content="text/html ; charset=UTF-8" />
    <title>BLABLA</title>
    <link rel="stylesheet" type="text/css" href="include/styles.css"> 
    <script language="javascript" >

    function hideElements(){
        document.getElementById("divAlbum").style.visibility="hidden";
    }

    function checkAlbum(form){
        if(form.checkAlbum.checked){
            document.getElementById("divAlbum").style.visibility="visible";
        }else{
            document.getElementById("divAlbum").style.visibility="hidden";
        }
    }

    </script>
</head>

I really don’t know what the problem is. I’ve checked the functions again and again. Any suggestions for the possible error? Thanks

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1 Answer

  1. Editorial Team

    The reason your button is not working is that this refers to the clicked input itself. The form property on the input refers to the value of the form attribute, not the actual form. In reality you don’t need the form attribute, you can simply use this.checked to see if the corresponding input is currently checked.

    Album:  <INPUT TYPE="checkbox" NAME="checkAlbum" onclick="checkAlbum(this)" id="idAlbum">

function checkAlbum(cb){
    if(cb.checked){
        document.getElementById("divAlbum").style.visibility="visible";
    }else{
        document.getElementById("divAlbum").style.visibility="hidden";
    }
}

    Beyond this I would suggest that you consider not applying your JavaScript inline. Keeping your code separate from your mark up improves readability and can help prevent errors. You might consider using the jQuery framework as it will make this sort of thing much easier.

    $(function(){
    $('#idAlbum').on('change', function() { 
        // use change instead of click in case there's a label involved
        $('#divAlbum').toggle(this.checked);
    });
});
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