Button don't disable on checkboxes validation-CodePudding

I have simple function where I have 3 checkboxes and trying to something like if are checkboxes unchecked, button should be disabled and if I check all (not just 1 or 2), button will activate

   function sub() {
     var a = document.getElementById("ch1");
     var b = document.getElementById("ch2");
     var c = document.getElementById("ch3");
     var btn = document.getElementById("btn")

    if (a.checked == true && b.checked == true && c.checked == true){  
    return btn.disabled = !!this.checked;
        
  }
  else {
    return btn.disabled;
}
   }

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Test</title>
</head>
<body>
    <input type="checkbox" id="ch1" >
    <input type="checkbox" id="ch2" >
    <input type="checkbox" id="ch3" >
    <button onclick="sub()" id="btn">Submit</button>
</body>
<script>


</script>
</html>

CodePudding user response：

You need to add an EventListener to the checkboxes and listen if their state change not add the script to a button itself:

let checkboxes = document.querySelectorAll('input[type="checkbox"]');

checkboxes.forEach(el =>
  el.addEventListener('change', function() {
    let checked_checkboxes = document.querySelectorAll('input[type="checkbox"]:checked');
    if (checked_checkboxes.length === checkboxes.length) {
      document.querySelector('#btn').removeAttribute('disabled');
    } else {
      document.querySelector('#btn').setAttribute('disabled', true);
    }
  })
)

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Test</title>
</head>
<body>
    <input type="checkbox" id="ch1" >
    <input type="checkbox" id="ch2" >
    <input type="checkbox" id="ch3" >
    <button onclick="sub()" id="btn" disabled>Submit</button>
</body>
<script>


</script>
</html>

CodePudding user response：

You need to set your button to disabled using a boolean. Whatever you think this.checked is, that's the issue.

btn.disabled = false;

Also if the button is enabled, it will just disable and never re-check .. You need to run sub() on the checkbox click ..

function sub() {
  var a = document.getElementById("ch1");
  var b = document.getElementById("ch2");
  var c = document.getElementById("ch3");
  var btn = document.getElementById("btn")

  if (a.checked == true && b.checked == true && c.checked == true) {
    btn.disabled = false;
  } else {
    btn.disabled = true;
  }
}

<input onclick="sub()" type="checkbox" id="ch1">
<input onclick="sub()" type="checkbox" id="ch2">
<input onclick="sub()" type="checkbox" id="ch3">
<button id="btn" disabled>Submit</button>

CodePudding user response：

document.getElementById("ch1").checked = true;
document.getElementById("ch2").checked = true;
document.getElementById("ch3").checked = true;
var checkedCount = 3;
var checkboxes = document.querySelectorAll("input[name=checkbox]");
checkboxes.forEach(function(checkbox){
checkbox.addEventListener('change', function() {
  if (this.checked) {
    console.log("Checkbox is checked..");
    checkedCount  ;
    console.log(checkedCount);
  } else {
    console.log("Checkbox is not checked..");
    checkedCount--;
    console.log(checkedCount);

  }
  if(checkedCount<3){
    document.getElementById("btn").disabled = true;
  }else{
    document.getElementById("btn").disabled = false;
  }
 });
})