Summary  
This chapter introduces JavaScript’s primitive data types (Number, BigInt, String, Boolean, null, undefined) and explains how to use the `typeof` operator for type checking.

General domain of usage  
Web development

### What are Data-types?

The values which we assign to the variables are of a specific type which is called the data type of that specific variable. We can assign numbers, string, boolean, null, undefined, array, object, functions, and symbols to variables.

### Introduction to different Data-types

Following is a brief introduction to the commonly used data types in JavaScript. We will go through these in detail in the upcoming chapters, but for now, let’s just get a basic understanding of all these.

- **Number**

Numbers are always floating-point numbers so both the integers as well as floating-point numbers are simply numbers in JavaScript.

let totalCoins=100;
console.log(totalCoins)

- **BigInt:**
`BigInt` is used to represent numbers of arbitrary lengths. A `BigInt` number can be generated by appending `n` at the end of a number.

// the "n" at the end means it's a BigInt
const bigInt = 12345678901234567890123n;
console.log(bigInt);

**Strings:**  
We use quotes to represent the strings. They are commonly used to deal with text.

let comment="good";
console.log(comment);

- **Boolean (logical type):**
In this type, we have only two values: `true` and `false`. We use `true` for “Yes”, and `false` is used for “No”. For instance, if we want to store the value of "It's raining" we will set the value to `true` and if it is not raining then we will set the value `false`.

let isRaining = true;
console.log(isRaining);

- **null:**
The `null` is a special value that represents “nothing”, “empty”, or “value unknown”.

let selectedColor = null;
console.log(selectedColor)

- **Undefined:**
In JavaScript, a default value of `undefined` is assigned to the variable if we do not assign a value to it.

### The `typeof` Operator:

The `typeof` operator is used to get the type of the value or variable. It’s useful to quickly check the types of values that are assigned to the variable.
To check the type we use the `typeof` keyword and pass the variable inside parentheses.

let drink="soda";
console.log('typeof("drink"):', typeof(drink));

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The syntax of the JavaScript programming language is the set of rules that defines how a JavaScript program will be written and interpreted (by both the runtime system and by human readers).

JavaScript is dynamically typed (also called loosely typed) scripting language. That is, in javascript variables can receive different data types over time. Datatypes are basically typed of data that can be used and manipulated in a program.

What are Data-types?

What are Data-types?

Introduction to different Data-types

The typeof Operator:

解答

The `typeof` Operator: