Ajax

Question

OK, this may sound silly... but how does the browser know I am requesting an AJAX for the astrosUrl? or can the function below be re-used for other requests? 
JavaScript
function getJSON(url) {
  const xhr = new XMLHttpRequest();
  xhr.open('GET', url);
  xhr.onload = () => {
    if(xhr.status === 200) {
      let data = JSON.parse(xhr.responseText);
      console.log(data);
    }
  };
  xhr.send();
}

I mean, I assume, here is when we call that particular URL, isn't it? but can the above be re-used for the others URL?
JavaScript
btn.addEventListener('click', () => getJSON(astrosUrl));
 
Also, why aren't we using:
JavaScript
(xhr.status === 200 && xhr.readyState === 4)

?

Steven Parker · Accepted Answer

The "getJSON" function knows which URL to get data from because the URL is passed to it as an argument when it is called.
This function isn't re-used because it only logs the data to the console, and the other task displays it on the page.
And it's not necessary to test "readyState" since the "onload" only runs when readyState is 4.

Welcome to the Treehouse Community

Looking to learn something new?

Silvia Ramos

Silvia Ramos

Ajax

1 Answer

Steven Parker

Steven Parker