Ajax中的表单，不使用表单标签

var xhr = new XMLHttpRequest();
var url = "your_server_url";
var params = "param1=value1&param2=value2"; // 表单数据

xhr.open("POST", url, true);
xhr.setRequestHeader("Content-type", "application/x-www-form-urlencoded");

xhr.onreadystatechange = function() {
  if (xhr.readyState == 4 && xhr.status == 200) {
    // 处理服务器响应
    console.log(xhr.responseText);
  }
};

xhr.send(params);

var url = "your_server_url";
var params = {
  method: "POST",
  headers: {
    "Content-type": "application/x-www-form-urlencoded"
  },
  body: "param1=value1&param2=value2" // 表单数据
};

fetch(url, params)
  .then(function(response) {
    // 处理服务器响应
    return response.text();
  })
  .then(function(data) {
    console.log(data);
  })
  .catch(function(error) {
    console.log(error);
  });