How to check if all checkboxes are unchecked

有一個按鈕是disabled, 希望有 checkbox 被勾的情況下, 自動啟用按鈕, 執行畫面:

解法:
https://stackoverflow.com/questions/14800954/how-to-check-if-all-checkboxes-are-unchecked

var textinputs = document.querySelectorAll('input[type=checkbox]'); 
var empty = [].filter.call( textinputs, function( el ) {
   return !el.checked
});

if (textinputs.length == empty.length) {
    alert("None filled");
    return false;
}

解法2: Checkbox Check Event Listener
https://stackoverflow.com/questions/14544104/checkbox-check-event-listener

Multiple checkboxes

Here’s an example of a list of checkboxes. To select multiple elements we use querySelectorAll instead of querySelector. Then use Array.filter and Array.map to extract checked values.

// Select all checkboxes with the name 'settings' using querySelectorAll.
var checkboxes = document.querySelectorAll("input[type=checkbox][name=settings]");
let enabledSettings = []

/*
For IE11 support, replace arrow functions with normal functions and
use a polyfill for Array.forEach:
https://vanillajstoolkit.com/polyfills/arrayforeach/
*/

// Use Array.forEach to add an event listener to each checkbox.
checkboxes.forEach(function(checkbox) {
  checkbox.addEventListener('change', function() {
    enabledSettings = 
      Array.from(checkboxes) // Convert checkboxes to an array to use filter and map.
      .filter(i => i.checked) // Use Array.filter to remove unchecked checkboxes.
      .map(i => i.value) // Use Array.map to extract only the checkbox values from the array of objects.
      
    console.log(enabledSettings)
  })
});

<label>
   <input type="checkbox" name="settings" value="forcefield">
   Enable forcefield
</label>
<label>
  <input type="checkbox" name="settings" value="invisibilitycloak">
  Enable invisibility cloak
</label>
<label>
  <input type="checkbox" name="settings" value="warpspeed">
  Enable warp speed
</label>

Multiple checkboxes with jQuery

let checkboxes = $("input[type=checkbox][name=settings]")
let enabledSettings = [];

// Attach a change event handler to the checkboxes.
checkboxes.change(function() {
  enabledSettings = checkboxes
    .filter(":checked") // Filter out unchecked boxes.
    .map(function() { // Extract values using jQuery map.
      return this.value;
    }) 
    .get() // Get array.
    
  console.log(enabledSettings);
});

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<label>
   <input type="checkbox" name="settings" value="forcefield">
   Enable forcefield
</label>
<label>
  <input type="checkbox" name="settings" value="invisibilitycloak">
  Enable invisibility cloak
</label>
<label>
  <input type="checkbox" name="settings" value="warpspeed">
  Enable warp speed
</label>