​x
 
<!DOCTYPE html>
<html>
<body>
​
<h1>JavaScript 回调</h1>
​
<p id="demo"></p>
​
<script>
function myDisplayer(some) {
  document.getElementById("demo").innerHTML = some;
}
​
function getFile(myCallback) {
  let req = new XMLHttpRequest();
  req.open('GET', "/demo/js/mycar.html");
  req.onload = function() {
    if (req.status == 200) {
      myCallback(this.responseText);
    } else {
      myCallback("Error: " + req.status);
    }
  }
  req.send();
}
​
getFile(myDisplayer); 
</script>
​
</body>
</html>
​