Get the value of checked checkbox?

Picking up values from multiple checkboxes

const checkedValues = [...document.querySelectorAll('input[type="checkbox"]:checked')]
                       .map(checkbox => checkbox.value);
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Here, querySelectorAll filters checked checkboxes. Then, map extracts their values. So, you obtain an array of checked values. It's like killing multiple checkboxes with one stone!

Real-time checkbox interactions

// Attaching event listener to each checkbox, we are all ears now!
document.querySelectorAll('input[type="checkbox"]').forEach(checkbox => {
  checkbox.addEventListener('change', function () {
    // Is it a bird? Is it a plane? No, it's a Checked Checkbox!
    if (this.checked) {
      console.log(`Checked ${this.value}`);
    } else {
      // Oops, checkbox changed its mind
      console.log(`Unchecked ${this.value}`);
    }
  });
});
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An event listener for every checkbox! The code above listens to change events, reacting immediately to user interactions.

Ol' Browser Compatibility

// Time travel to support old browsers
var checkboxes = document.getElementsByClassName('messageCheckbox');
var checkedOne;
for (var i = 0; i < checkboxes.length; i++) {
  if (checkboxes[i].type === 'checkbox' && checkboxes[i].checked) {
    checkedOne = checkboxes[i].value; // gotcha!
    break; // Found a checked box, time to pack up & go home!
  }
}
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Not all heroes wear capes! This code ensures checkbox value retrieval even in legacy browsers using getElementsByClassName.

Grouped Checkboxes - Organized Value Retrieval

// Efficient checkbox gathering from multiple groups
const checkedGroupValues = [...document.getElementsByName('groupName')]
                            .filter(checkbox => checkbox.checked)
                            .map(checkbox => checkbox.value);


When dealing with multiple checkbox groups, this snippet allows you to get the values of all checked boxes for a specific group. It's like having x-ray vision for group names!

Concatenating jQuery – Peeling the Syntax

const checkedValue = $('input[type="checkbox"]:checked').val();
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When jQuery is at play, A checked checkbox value is just one $().val() away!

Staying Regular with Consistency

To prevent mix-ups, limit the selection to only one checkbox if expecting a single result. This maintains consistency acorss the application.

Performance Optimization

Avoid redundant trips to your DOM plantation! This means reducing excessive checkbox state checks. Instead, be smart with your event listeners, and keep your state updates crisp and accurate.