typeof Function

The typeof operator returns a string indicating the type of the unevaluated operand. It is useful for determining the type of a variable or expression in JavaScript.

Syntax

The syntax for the typeof operator is:

typeof operand

Here, operand is the expression whose type is to be returned.

Return Values

The typeof operator can return the following values:

• undefined: If the variable is not defined.
• boolean: For boolean values.
• number: For numeric values.
• bigint: For big integer values.
• string: For string values.
• symbol: For symbol values.
• function: For function values.
• object: For objects, arrays, and null.

Examples

Here are some examples of using the typeof operator:

typeof "Hello"; // Returns "string"
typeof 42; // Returns "number"
typeof true; // Returns "boolean"
typeof undefined; // Returns "undefined"
typeof {name: "John"}; // Returns "object"
typeof [1, 2, 3]; // Returns "object"
typeof function() {}; // Returns "function"
typeof null; // Returns "object" (this is a known quirk in JavaScript)