Check the type of a variable in JavaScript using `typeof`

To check the type of a given variable or value we use the typeof operator, which returns the type as a string.

const input = "1";
const type = typeof input;
console.log(type);
//=> 'string'

The possible return values of the typeof operator are:

• undefined
• boolean
• number
• string
• object
• bigint
• symbol
• function

There is a gotcha here, odd enough the type of the value null is "object", for the historic reason why I recommend to read why at 2ality.com.