How to get datatype in JavaScript

How to get datatype in JavaScript?

1. Using typeof Operator

The JavaScript `typeof` operator is used to determine the type of a variable or value. It returns a string indicating the data type, such as `"number"`, `"string"`, `"boolean"`, `"object"`, `"undefined"`, or `"function"`.

For example get data type javascript:

typeof 42          // "number"
typeof 'hello'     // "string"
typeof true        // "boolean"
typeof undefined   // "undefined"
typeof {}          // "object"
typeof []          // "object"
typeof null        // "object"

In JavaScript, when a variable is declared but not assigned a value, its value is automatically set to `undefined`. The type of such a variable is also `undefined`.

let product;    // Value is undefined, type is undefined

An empty string (`""`) is a valid value in JavaScript with a specific type of `string`. It's different from `undefined`, which indicates a variable has no value assigned. An empty string is not the same as `undefined`.

let product = "";    // The value is "", the typeof is "string"