Javascript发送变量post

var xhr = new XMLHttpRequest();
var url = "http://example.com/api"; // 替换为实际的后端接口地址

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

var data = "var1=value1&var2=value2"; // 替换为实际的变量和数值

xhr.onreadystatechange = function() {
  if (xhr.readyState === 4 && xhr.status === 200) {
    console.log(xhr.responseText); // 服务器返回的响应数据
  }
};

xhr.send(data);

var url = "http://example.com/api"; // 替换为实际的后端接口地址

var data = {
  var1: "value1",
  var2: "value2"
}; // 替换为实际的变量和数值

fetch(url, {
  method: "POST",
  headers: {
    "Content-Type": "application/json"
  },
  body: JSON.stringify(data)
})
.then(response => response.json())
.then(data => {
  console.log(data); // 服务器返回的响应数据
})
.catch(error => {
  console.error(error);
});