js回调函数是什么

// 普通函数作为回调
function greet(name, callback) {
    console.log('Hello, ' + name);
    callback();
}

function sayGoodbye() {
    console.log('Goodbye!');
}

greet('Alice', sayGoodbye);

// 匿名函数作为回调
document.getElementById('myButton').addEventListener('click', function () {
    console.log('Button was clicked!');
});

// 异步请求中的回调
fetch('https://api.example.com/data')
    .then(function (response) {
        console.log('Data received:', response);
    })
    .catch(function (error) {
        console.error('Error:', error);
    });