Chceking Checkbox State

To determine if a checkbox is checked:

const isChecked = $('input[type="checkbox"]').is(':checked');

This returns true if selected, otherwise false.

Retrieving Checked Checkbox Values

Collect values of all checked checkboxes with a specific name:

const selectedValues = [];
$('input[name="test"]:checked').each((index, element) => {
    selectedValues.push($(element).val());
});

Checkbox Selection Controls

Implemetn common selection behaviors:

$(document).ready(() => {
    $('#selectAll').on('click', () => {
        $('input[name="checkbox"]').prop('checked', true);
    });

    $('#deselectAll').on('click', () => {
        $('input[name="checkbox"]').prop('checked', false);
    });

    $('#selectOdd').on('click', () => {
        $('input[name="checkbox"]:odd').prop('checked', true);
    });

    $('#toggleSelection').on('click', () => {
        $('input[name="checkbox"]').each(function() {
            $(this).prop('checked', !$(this).prop('checked'));
        });
    });
});

Getting Select Dropdown Value

Retrieve the currently selected value from a dropdown:

const selectedOption = $('#select').val();

Obtaining Selected Radio Button Value

Multiple equivalent approaches to get the value of a selected radio button:

$('input:radio:checked').val();
$('input[type="radio"]:checked').val();
$('input[name="rd"]:checked').val();

Selecting Specific Radio Buttons

Set the first radio button as selected:

$('input:radio:first').prop('checked', true);

Set the last radio button as selected:

$('input:radio:last').prop('checked', true);

Select a radio button by index (zero-based):

$('input:radio').eq(2).prop('checked', true); // selects third option

Alternatively using slice (selects second option):

$('input:radio').slice(1, 2).prop('checked', true);

Select by value:

$('input:radio[value="rd2"]').prop('checked', true);