JavaScript - what is the difference between let and var?

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Created by:

AnnLen

1777

1. Main differences between `let` and `var` keywords are:

let keyword varialbes do not have varialble hoisting.
variable hoisting is shifting varialbe declarations to top of source code making them accessible above.

Example 1:

<!doctype html>
<html>
<body>
  <script>

    'use strict';

    a = 2; // variable hosting allows for assigning before declaration
    console.log(a);

    var a;

  </script>
</body>
</html>

Output:

Example 2:

<!doctype html>
<html>
<body>
  <script>

    'use strict';

    var a = 2;
    console.log(a);

  </script>
</body>
</html>

Output:

let keyword varialbes can be created in different scopes:

	`let` keyword variables	`var` keyword variables
global scope	yes	yes
function scope	yes	yes
curly braces scope	yes	no

2. Tips

ALWAYS use let keyword.

1. Main differences between let and var keywords are:

2. Tips

See also

1. Main differences between `let` and `var` keywords are: