原生JavaScript ajax实现示例

// 原生JavaScript ajax实现示例
function ajax(method, url, data, success) {
  var xhr = null;

  if (window.XMLHttpRequest) {
    xhr = new XMLHttpRequest();
  } else {
    xhr = new ActiveXObject('Microsoft.XMLHTTP');
  }

  var paramArr = [];
  for (var key in data) {
    paramArr.push(key + '=' + data[key]);
  }
  var postData = paramArr.join('&');

  if (method.toLowerCase() === 'post') {
    xhr.open(method, url, true);
    xhr.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded;charset=UTF-8');
    xhr.send(postData);
  } else if (method.toLowerCase() === 'get') {
    xhr.open(method, url + '?' + postData, true);
    xhr.send();
  }

  xhr.onreadystatechange = function () {
    if (xhr.readyState === 4) {
      if (xhr.status === 200) {
        success(xhr.responseText);
      }
    }
  };
}

// 使用示例
var sendData = {
  name: 'ChatGPT',
  age: '2'
};
ajax('post', '/api/user', sendData, function (data) {
  console.log('请求成功，返回数据：', data);
});