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

July 14, 2022  ‐ 1 min read

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.