Lesson 14

Strings Basics

Strings are used to represent text. A string is a sequence of characters wrapped in single, double, or backticks.

What is a String?
Creating Strings
Accessing Characters
String Length
Common Operations
String Methods
Template Literals

let message = "Hello, World!"

Index	0	1	2	3	4	5	6	7	8	9	10	11	12
Char	H	e	l	l	o	,	␣	W	o	r	l	d	!

Length: 13

Sequence of Characters

A string is a collection of characters.

❝

Can Use Quotes

Use single ( ' ), double ( " ) or backticks ( ` ).

Zero-based Indexing

First character is at index 0.

Has a Length

Use .length to find the number of characters.

JavaScript

1let single = 'Hello';
2let double = "World";
3let backtick = `Master DSA`;
4
5let message = "Hello, World!";
6console.log(message[0]);       // H
7console.log(message[7]);       // W
8console.log(message.length);   // 13

Output

Your output will appear here...

Operation	Example	Result	Description
Concatenation	`'Hello' + ' ' + 'DSA'`	Hello DSA	Combines two or more strings.
toUpperCase()	`'hello'.toUpperCase()`	HELLO	Converts string to uppercase.
toLowerCase()	`'HELLO'.toLowerCase()`	hello	Converts string to lowercase.
includes()	`'Master DSA'.includes('DSA')`	true	Checks if substring exists.
slice()	`'Master DSA'.slice(7, 10)`	DSA	Extracts part of a string.
replace()	`'I love JS'.replace('JS', 'DSA')`	I love DSA	Replaces substring.

```
str.length
```
// Length of string
```
str[index]
```
// Character at index
```
str.charAt(index)
```
// Character at index
```
str.slice(start, end)
```
// Substring
```
str.toUpperCase()
```
// Uppercase string
```
str.toLowerCase()
```
// Lowercase string
```
str.includes(sub)
```
// Check substring

Strings are immutable in JavaScript. Methods like toUpperCase() return a new string instead of changing the original.