js 获取post 响应参数

var xhr = new XMLHttpRequest();
xhr.open('POST', 'https://example.com/api', true);
xhr.setRequestHeader('Content-Type', 'application/json');

xhr.onreadystatechange = function () {
    if (xhr.readyState === 4 && xhr.status === 200) {
        var response = JSON.parse(xhr.responseText);
        console.log(response);
    }
};

var data = JSON.stringify({ key: 'value' });
xhr.send(data);

fetch('https://example.com/api', {
    method: 'POST',
    headers: {
        'Content-Type': 'application/json'
    },
    body: JSON.stringify({ key: 'value' })
})
.then(response => {
    if (!response.ok) {
        throw new Error('Network response was not ok');
    }
    return response.json();
})
.then(data => {
    console.log(data);
})
.catch(error => {
    console.error('There has been a problem with your fetch operation:', error);
});