The typeof operator is used in either of the following ways:

1. typeof operand
2. typeof ( operand )

The typeof operator returns a string indicating the type of the unevaluated operand. operand is the string, variable, keyword, or object for which the type is to be returned. The parentheses are optional.

Suppose you define the following variables:

The typeof operator returns the following results for these variables:

typeof myFun is object
typeof shape is string
typeof size is number
typeof today is object
typeof dontExist is undefined

For the keywords true and null, the typeof operator returns the following results:

typeof true is boolean
typeof null is object
For a number or string, the typeof operator returns the following results:
typeof 62 is number
typeof 'Hello world' is string
For property values, the typeof operator returns the type of value the property contains:
typeof document.lastModified is string
typeof window.length is number
typeof Math.LN2 is number
For methods and functions, the typeof operator returns results as follows:
typeof blur is function
typeof eval is function
typeof parseInt is function
typeof shape.split is function
For predefined objects, the typeof operator returns results as follows:
typeof Date is function
typeof Function is function
typeof Math is function
typeof Option is function
typeof String is function