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// Example code in JavaScript explaining data types

// Number type
let age;
let height = 170.5;

// String type
let name = 'John';
let message = 'Hello there!';

// Boolean type
let isStudent = true;
let hasDriverLicense = false;

// Object type
let student = {
  name: 'John',
  age: 16,
  grade: '10th grade',
};

// Array type
let fruits = ['Apple', 'Banana', 'Grape'];

// Data type check
console.log(`Type of age: ${typeof age}`); // number

console.log(`Type of height: ${typeof height}`); // number

console.log(`Type of name: ${typeof name}`); // string

console.log(`Type of message: ${typeof message}`); // string

console.log(`Type of isStudent: ${typeof isStudent}`); // boolean

console.log(`Type of hasDriverLicense: ${typeof hasDriverLicense}`); // boolean

console.log(`Type of student: ${typeof student}`); // object

console.log(`Type of fruits: ${typeof fruits}`); // object

# What are Data Types?

Data types refer to the `type` of data such as characters, numbers, and true/false values.

Programming languages provide various data types to process and store data.

In JavaScript, the following data types are used:

 

## Number

This represents numeric values such as integers, floats, and natural numbers.

```javascript title="Number Data Type"
let age = 16;
let height = 170.5;
```

 

## String

Strings represent textual information. Any letter, word, or sentence enclosed in quotes (' ', " ") is considered a string.

```javascript title="String Data Type"
let name = 'John';
let message = 'Hello there!';
```

 

## Boolean

The Boolean data type can only have one of two values: `true` or `false`, similar to turning a switch on or off.

```javascript title="Boolean Data Type"
let isStudent = true;
let hasDriverLicense = false;
```

 

## Object

An object is a data type used to store multiple values or complex entities. For instance, a student object can hold information like name, age, and grade.

```javascript title="Object Data Type"
let student = {
 name: 'John',
 age: 16,
 grade: '11th Grade',
};
```

 

## Array

An array lists data of the same type, as shown below.

```javascript title="Array Data Type"
let fruits = ['Apple', 'Banana', 'Grape'];
```

 

## null

`null` is a special value that represents 'no value'.

You assign `null` to a variable when you want to explicitly indicate that it does not have any value yet.

```javascript title="null Data Type"
let emptyValue = null;
```

 

## undefined

`undefined` indicates that a variable has been declared but has not yet been assigned a value.

It means the value is not defined.

If you declare a variable and do not initialize it, JavaScript automatically assigns it the value of `undefined`.

```javascript title="undefined Data Type"
let notDefinedYet;
console.log(notDefinedYet); // Output: undefined
```

While both `null` and `undefined` represent the concept of a lack of value, they are used in different contexts and have distinct meanings.

`null` is used when you explicitly want to express the absence of any value, whereas `undefined` signifies the initial state of a variable or a situation where no value has been passed where one is expected.

The Boolean data type can hold only one of two values: true or false. It is commonly used in programming for handling conditionals and logic flow.

What are Data Types?

Number

String

Boolean

Object

Array

null

undefined

Which of the following data types represents a true/false value?

Which of the following data types represents a `true/false` value?