Case-sensitivity

Javascript is case-sensitive. The variables, function names, and operators are all case-sensitive. A variable named test is different from a variable named Test.

 
<!DOCTYPE HTML>
<html>
<head>
<title>Example</title>
  <script type="text/javascript">
      var a = 'a';
      var A = 'A';
    document.writeln(a);
    document.writeln(A);
  </script>
</head>
<body>
</body>
</html>
  
Click to view the demo
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Language Basics:
  1. Case-sensitivity
  2. Identifiers
  3. Comments
  4. Strict Mode
  5. Statements
  6. Keywords And Reserved Words
  7. Variables