Searching and changing the value of the checkbox with javascript

Question

I’m trying to search and change the values of a checkbox using Javascript. The intention is, when the JS function is called, to check if the checkbox is set. If not, seven-a as checked, and vice versa. However, when trying to read the checkbox state the following error is shown:"Cannot read Property 'checked' of null"

My last attempt so far was as follows::

<label for="letrasMinusculas">
<img src="images/checked.png" id="imgLetrasMinusculas" onclick="changeIcon(letrasMinusculas)">
</label>

<input id="letrasMinusculas" class="boxOculto" name="letrasMinusculas" type="checkbox" checked>

And in Javascript:

function changeIcon(id){
                           var status = document.getElementById(id);
                           if (status.checked){
                            alert("Verdadeiro");
                           }
                           else{alert("Falso");}
                    }

Note: The checkbox receives the class "boxOculto" (display: None) because I prefer to use a label with image for the user to click for customization.

Answer 1

Your function is working properly, what are you passing as parameter id ? has to be 'letrasMinusculas', in your This you can set checked = true if this is what you really need.

Example:

function changeIcon(id) {
  var status = document.getElementById(id);
  if (status.checked) {
    alert("Verdadeiro");
  } else {
    alert("Falso");
    status.checked = true;
  }
}

changeIcon('letrasMinusculas');

<input id="letrasMinusculas" class="boxOculto" name="letrasMinusculas" type="checkbox" checked>