Ajax 不会触发 onreadystatechange

Question

我知道该 URL 正在按预期工作，因为我将其记录到控制台，这很好。但是，当 readyState == 4 和 status == 200 时，我无法将“好消息”登录到控制台。我尝试删除 readState，但它仍然不会记录。我尝试记录状态，它只会触发一次，值为 0。这是我第一次使用 Ajax，因此不胜感激。

function setupRequest(){
  var bttn = document.querySelector('#send');

  bttn.addEventListener('click', sendData)
}

setupRequest();

function sendData () {

console.log('ran')
  var url = 'localhost/bev/drinks.php';

  var data = document.getElementById('input').value;
  url += '?' + 'alcohol=' + data;

console.log(url)

 var request = new XMLHttpRequest();
 request.onreadystatechange = function () {
  if (this.readyState == 4 && this.status == 200) {
    console.log('good news')
            console.log(this.responseText)
        } else {
    console.log(this.status)
        }
    }

 request.open('GET', url, true);
 request.send;

  console.log('sent')

}

Answer 1

您需要实际致电send()。每当你说request.send;

function setupRequest() {
  var bttn = document.querySelector('#send');

  bttn.addEventListener('click', sendData)
}

setupRequest();

function sendData() {

  console.log('ran')
  var url = 'https://jsonplaceholder.typicode.com/posts';

  var data = document.getElementById('input').value;
  //url += '?' + 'alcohol=' + data;

  console.log(url)

  var request = new XMLHttpRequest();
  request.onreadystatechange = function() {
    if (this.readyState == 4 && this.status == 200) {
      console.log('good news')
      console.log(this.responseText)
    } else {
      console.log(this.status)
    }
  }

  request.open('GET', url, true);

  // You wrote (without parentheses):
  ///////////////////
  // request.send; //
  ///////////////////

  // You need to write
  request.send();

  console.log('sent')

}

<button type="button" id="send">Btn</button>
<input type="text" id="input">