js的ajax的完整写法

// GET请求示例
function makeGetRequest(url, callback) {
    var xhr = new XMLHttpRequest();
    xhr.onreadystatechange = function() {
        if (xhr.readyState === 4 && xhr.status === 200) {
            callback(xhr.responseText);
        }
    };
    xhr.open('GET', url, true);
    xhr.send();
}

// POST请求示例
function makePostRequest(url, data, callback) {
    var xhr = new XMLHttpRequest();
    xhr.onreadystatechange = function() {
        if (xhr.readyState === 4 && xhr.status === 200) {
            callback(xhr.responseText);
        }
    };
    xhr.open('POST', url, true);
    xhr.setRequestHeader('Content-Type', 'application/json');
    xhr.send(JSON.stringify(data));
}

// 使用示例
makeGetRequest('https://api.example.com/data', function(response) {
    console.log('GET Response:', response);
});

var postData = { key: 'value' };
makePostRequest('https://api.example.com/submit', postData, function(response) {
    console.log('POST Response:', response);
});