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Variables

Declaring variables​

There are three keywords to be able to declare a variable

  • let
  • const
  • var

Let​

The let keyword is used to create a variable that can be changed.

Const​

The const keyword is used to create a variable that can not be changed.

Var​

The var keyword is used to store any type of variables, but is now deprecated and let and const should be used instead as these are more specific if they are dynamic aor static.

Initializing a variable​

This is done by assigning a value to the variable

let name = "James";

or

let name;
name = "James";

Hoisting​

Varaibles that are declared using the var or function keywords are automatically moved to the top of the script, no matter where they are declared in the code. This does not apply to const and let keywords.

console.log(name);
name = "James";
var name;

is the same as

var name;
console.log(name);
name = "James";

Note: When the variable declartion is hoisted, it is set to undefined, so in this example the console.log would output undefined.

Variable Scope​

Variable scope refers to who can access a variable based on where it is declared.

  • Global
  • Module
  • Function