JavaScript Strings 🎭

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JavaScript Strings 🎭
Strings in JavaScript are sequences of characters enclosed in single ('), double ("), or template literals (` `).

1️⃣ Creating Strings
✅ 1. Using Quotes (' or " - Preferred)

let singleQuote = 'Hello';

let doubleQuote = "World";

✅ 2. Using Template Literals (` ` - Best for Dynamic Content)

let name = "Alice";

let message = `Hello, ${name}!`; 

console.log(message); // Output: Hello, Alice!

✅ 3. Using new String() (Not Recommended)

let strObj = new String("Hello");

console.log(typeof strObj); // Output: object

📌 Avoid new String(), as it creates an object instead of a primitive string.

2️⃣ Common String Methods
Method Description Example
.length Returns the length of the string "Hello".length // 5
.toUpperCase() Converts to uppercase "hello".toUpperCase() // "HELLO"
.toLowerCase() Converts to lowercase "WORLD".toLowerCase() // "world"
.trim() Removes spaces from both ends " hello ".trim() // "hello"
.charAt(index) Returns the character at an index "Java".charAt(1) // "a"
.indexOf("str") Finds the first occurrence "hello".indexOf("l") // 2
.lastIndexOf("str") Finds the last occurrence "hello".lastIndexOf("l") // 3
.includes("str") Checks if a string contains another string "Hello".includes("He") // true
.startsWith("str") Checks if string starts with a value "JavaScript".startsWith("Java") // true
.endsWith("str") Checks if string ends with a value "file.txt".endsWith(".txt") // true
.slice(start, end) Extracts part of a string "Hello".slice(1, 4) // "ell"
.substring(start, end) Similar to slice() but can't use negative indexes "Hello".substring(1, 4) // "ell"
.substr(start, length) Extracts a substring with a length "Hello".substr(1, 3) // "ell"
.replace("old", "new") Replaces first occurrence "Hello World".replace("World", "JS") // "Hello JS"
.replaceAll("old", "new") Replaces all occurrences "abc abc".replaceAll("abc", "xyz") // "xyz xyz"
.split("delimiter") Splits a string into an array "a,b,c".split(",") // ["a", "b", "c"]

3️⃣ Examples of String Manipulation

✅ 1. Changing Case

let text = "JavaScript";

console.log(text.toUpperCase()); // "JAVASCRIPT"

console.log(text.toLowerCase()); // "javascript"

✅ 2. Trimming Spaces

let userInput = "   hello world   ";

console.log(userInput.trim()); // "hello world"

✅ 3. Extracting Parts of a String

let str = "Hello, World!";

console.log(str.slice(7, 12)); // "World"

console.log(str.substring(7, 12)); // "World"

console.log(str.substr(7, 5)); // "World"

✅ 4. Checking if a String Contains a Word

let sentence = "The quick brown fox";

console.log(sentence.includes("quick")); // true

console.log(sentence.startsWith("The")); // true

console.log(sentence.endsWith("fox")); // true

✅ 5. Replacing Text

let phrase = "I love Python";

let newPhrase = phrase.replace("Python", "JavaScript");

console.log(newPhrase); // "I love JavaScript"

✅ 6. Splitting a String into an Array

let csv = "apple,banana,cherry";

let fruits = csv.split(",");

console.log(fruits); // ["apple", "banana", "cherry"]

4️⃣ Template Literals ( ) - String Interpolation
Use backticks (`) for easier multi-line strings and variables inside strings.

✅ 1. Embedding Variables

let name = "Alice";

let age = 25;

let greeting = `Hello, my name is ${name} and I am ${age} years old.`;

console.log(greeting);

✅ 2. Multi-Line Strings

 

let message = `This is

a multi-line

string.`;

console.log(message);

5️⃣ Summary
✅ Strings are enclosed in ', ", or `.
✅ Use string methods for manipulation (toUpperCase(), trim(), slice(), etc.).
✅ Use template literals ( ) for easy variable insertion.

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    Date: 2025-03-29 00:00:00.000000