JS Strings

Overview

Strings in JavaScript are sequences of characters enclosed within single ('') or double ("") quotes. They are essential for representing textual data and are extensively used in programming for text manipulation, output formatting, and more.

Creating Strings

Strings can be created using single or double quotes.

        
            let singleQuotes = 'This is a string.';
let doubleQuotes = "Another string.";
        
    

String Concatenation

Strings can be concatenated using the + operator.

        
            let firstName = "John";
let lastName = "Doe";
let fullName = firstName + " " + lastName;   // John Doe

console.log(fullName) // John Doe
        
    

Escape Characters

Special characters can be included in strings using escape sequences.

        
            let text = "This is a \"quote\" inside a string.";

console.log(text) // This is a "quote" inside a string.

        
    

String Methods

• toUpperCase() Converts a string to uppercase.
• toLowerCase() Converts a string to lowercase.
• indexOf() Returns the index of a specified substring.
• lastIndexOf() Returns the last index of a substring.
• includes() Checks if a substring exists within a string.
• replace() Replaces a substring with another substring.
• split() Splits a string into an array of substrings.
• join() Joins array elements into a single string.
• substring() Extracts a substring from a string.
• trim() Removes leading and trailing whitespace.
• trimStart() Removes leading whitespace.
• trimEnd() Removes trailing whitespace.
• padStart() Pads a string with characters from the start.
• padEnd() Pads a string with characters at the end.
• charAt() Returns the character at a specific index.
• charCodeAt() Returns the Unicode value of a character.
• toString() Converts a value to a string.
• Template literals: Enhanced strings using backticks (`) for string interpolation.

        
            let text = "   Hello, world!   ";
let trimmedStart = text.trimStart();      // "Hello, world!   "
let trimmedEnd = text.trimEnd();          // "   Hello, world!"
let paddedStart = text.padStart(20, "-"); // "-----   Hello, world!   "
let paddedEnd = text.padEnd(20, "-");     // "   Hello, world!   -----"
let character = text.charAt(7);           // "w"
let unicodeValue = text.charCodeAt(7);    // 119
let replacedText = text.replace("world", "Universe");  // "   Hello, Universe!   "
let uppercaseText = text.toUpperCase();   // "   HELLO, WORLD!   "

console.log(text)
console.log(trimmedStart)
console.log(trimmedEnd)
console.log(paddedStart)
console.log(paddedEnd)
console.log(character)
console.log(unicodeValue)
console.log(replacedText)
console.log(uppercaseText)
        
    

Template Literals (``)

Template literals allow string interpolation and multiline strings.

        
            let name = "Alice";
let age = 30;
let greeting = `Hello, ${name}! You are ${age} years old.`;

console.log(greeting) // Hello, Alice! You are 30 years old.
        
    

Summary

Strings are fundamental data types in JavaScript used to represent text. With various methods and operations available, strings are versatile tools for text manipulation, formatting, and more.