Introduction to Strings and Arrays

String Methods

Assuming all readers have a basic understanding of arrays and strings, we won’t dwell on those concepts. Instead, here’s a concise list of frequently used string methods:

• charAt(index): Retrieves a character at a specific index in a string.

const text = "Hello, World!";
const character = text.charAt(7); // Returns 'W'

• charCodeAt: used to retrieve the Unicode value (integer representation) of a character at a specified index within a string.

const text = "Hello, World!";
const index = 7; // Index of the character 'W'
const charCode = text.charCodeAt(index); // 87

• length: Provides the length of a string.

const text = "Sample Text";
const length = text.length; // Returns 11

• toUpperCase() and toLowerCase(): Converts text to uppercase or lowercase.

const text = "Convert Me";
const upper = text.toUpperCase(); // Returns "CONVERT ME"
const lower = text.toLowerCase(); // Returns "convert me"

• concat(str2): Combines two strings into one.

const str1 = "Hello, ";
const str2 = "World!";
const combined = str1.concat(str2); // Returns "Hello, World!"

• indexOf(substring): Identifies the index of the first occurrence of a substring.

const text = "This is a sample text.";
const index = text.indexOf("sample"); // Returns 10

• substring(startIndex, endIndex): Extracts a section of a string, starting at the start index(inclusive) and ending at the end index (exclusive).

const text = "Extract this part.";
const substring = text.substring(8, 18); // Returns "this part"

• substr(start, length): extracts characters from the string, starting at the start index and continuing for a specified length of characters. It allows you to use a negative start index, which counts from the end of the string.

const text = "Hello, World!";
const sub = text.substr(7, 5); // Returns "World"

• split(separator): Divides a string into an array of substrings using a separator.

const text = "Apple, Banana, Cherry";
const fruits = text.split(", "); // Returns ["Apple", "Banana", "Cherry"]

• trim(): Eliminates excess whitespace from the string’s beginning and end. Also, there are methods trimStart(), trimEnd()

const text = "   Trim me!   ";
const trimmed = text.trim(); // Returns "Trim me!"

• replace(oldValue, newValue): Substitutes instances of a specific substring with a new one.

const text = "Replace these words.";
const newText = text.replace("these", "those"); // Returns "Replace those words."

• padStart(maxLength, fillString): is used to pad the beginning (left side) of a string to reach the specified maxLength. It adds characters from fillString to the left of the original string until it reaches the desired length.

const text = "123";
const paddedText = text.padStart(5, "0"); // Returns "00123"

• padEnd(maxLength, fillString): is used to pad the end (right side) of a string to reach the specified maxLength. It appends characters from fillString to the right of the original string until it reaches the desired length.

const text = "123";
const paddedText = text.padEnd(5, "*"); // Returns "123**"