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JavaScript AJAX Basics AJAX Concepts Create an XMLHttpRequest Object

seth aruby
seth aruby
9,354 Points

Why const vs let when assigning new XMLHttpRequest() object to variable?

Noticed that when completing this challenge using the 'let' keyword for assigning XMLHttpRequest() object to the variable was failing. So had to use const instead. Wondering why? Thanks in advance...

app.js
let request = new XMLHttpRequest();
index.html
<!DOCTYPE html>
<html>
<head>
  <meta charset="utf-8">
  <title>AJAX with JavaScript</title>
  <script src="app.js"></script>
</head>
<body>
  <div id="main">
    <h1>AJAX!</h1>
  </div>
  <div id="footer"></div>
</body>
</html>

1 Answer

Steven Parker
Steven Parker
221,324 Points

That does seem odd. I have two wild guesses:

  • they wanted to enforce the "best practice" use of "const" over "let" (but "var" also works)
  • an older challenge checking mechanism was only partially updated for ES2015 syntax