function sendSyncRequest(url, method, data) {
    const xhr = new XMLHttpRequest();
    xhr.open(method, url, false);

    if (method === 'POST' || method === 'PUT') {
        xhr.setRequestHeader('Content-Type', 'application/json');
        xhr.send(JSON.stringify(data));
    } else {
        xhr.send();
    }

    return JSON.parse(xhr.responseText);
}
let a = sendSyncRequest("https://httpbin.tianyunperfect.cn/post","POST", {"a": 1})
console.log(a);