Javascript - Array,String, Functions,Types of variables

ARRAY:

--> An array in JavaScript is a data structure used to store multiple values in a single variable.
--> Arrays can hold different types of data, including numbers, strings, objects, and even other arrays.
--> They are zero-indexed, meaning the first element is at index 0.

Creating an Array:

1. Using square brackets-[]

Ex:

let fruits = ["apple", "banana", "cherry"];

2. Using the Array constructor-new Array

Ex:

let numbers = new Array(1, 2, 3, 4);
console.log(numbers);

Output:
[1, 2, 3, 4]

String

--> In JavaScript, a string is a sequence of characters used to represent text.
--> Strings in JavaScript are immutable, they cannot be changed.

Declaring Strings

Strings can be defined using:

Double quotes: "Hello"
Single quotes: 'Hello'
Template literals: `Hello`

Note:

--> Strings created with single or double quotes work the same.
--> There is no difference between the two.
--> Templates are strings enclosed in backticks(``)
--> Templates allow single and double quotes inside a string.

String Methods:

1. trim() - Removes whitespace from both ends of a string.
2. toLowerCase() - Converts all characters in a string to lowercase.
3. toUpperCase() - Converts all characters in a string to uppercase.
4. includes() - Checks if a substring exists within the string.
5. indexOf() - Finds the index of the first occurrence of a substring.
6. replace() - Replaces the first occurrence of a substring with another.
7. replaceAll() - Replaces all occurrences of a substring with another.
8. split() - Splits a string into an array based on a separator.
9. substring() - Extracts a portion of the string between two indices.
10. slice() - Extracts a part of a string using start and end indices.
11. startsWith() - Checks if a string starts with a specific substring.
12. endsWith() - Checks if a string ends with a specific substring.
13. match() - Matches the string against a regular expression.
14. padStart() - Pads the string from the start with a specific character.
15. padEnd() - Pads the string from the end with a specific character.
16. concat() - Combines two or more strings into one.
17. toString() - Converts a value to a string.
18. localeCompare() - Compares two strings for sorting based on locale.
19. charAt() - Returns the character at a specific index in the string.
20. charCodeAt() - Method returns the code of the character at a specified index in a string
21. length - Retrieves the number of characters in the string.

Functions

--> A function is a block of reusable code that performs a specific task.
--> It executes the block of code only when it is called.
--> Function is defined with the function keyword, followed by a name, followed by parentheses ().
--> Function names can contain letters, digits, underscores, and dollar signs (same rules as variables).
--> The parentheses may include parameter names separated by commas:
(parameter1, parameter2, ...)

Syntax:

function name(parameter1, parameter2, parameter3) {
// code to be executed
}

Function Return

The return statement in JavaScript is used inside a function to return a value to the point where the function was called.

Types of variables:

1. Global variable
2. Local variable

Switch Statement:

--> The switch statement in JavaScript is used to execute different blocks of code based on different values of an expression.
--> It is an alternative to writing multiple if...else statements when dealing with multiple conditions.
--> switch statement is used to select one of many code blocks to be executed.

How it works?

• The switch expression is evaluated once.
• The value of the expression is compared with the values of each case.
• If there is a match, the associated block of code is executed.
• If there is no match, the default code block is executed.

Syntax: