js勾选checkbox

var checkbox = document.getElementById('myCheckbox');

if (checkbox.checked) {
    console.log('Checkbox is checked!');
} else {
    console.log('Checkbox is not checked.');
}

checkbox.checked = true;

checkbox.checked = !checkbox.checked;

checkbox.addEventListener('change', function() {
    if (this.checked) {
        console.log('Checkbox was checked!');
    } else {
        console.log('Checkbox was unchecked.');
    }
});

document.addEventListener('DOMContentLoaded', function() {
    // Your checkbox handling code here
});

function syncCheckboxes() {
    var masterCheckbox = document.getElementById('masterCheckbox');
    var checkboxes = document.querySelectorAll('.slaveCheckbox');
    checkboxes.forEach(function(checkbox) {
        checkbox.checked = masterCheckbox.checked;
    });
}

document.getElementById('masterCheckbox').addEventListener('change', syncCheckboxes);