Understanding JavaScript Strings 💡

Creating Strings

const singleQuotes = 'Hello, world!'
const doubleQuotes = 'Hello, world!'
const templateLiteral = `Hello, world!`

console.log(singleQuotes) // Output: Hello, world!
console.log(doubleQuotes) // Output: Hello, world!
console.log(templateLiteral) // Output: Hello, world!

Template literals allow for multi-line strings and embedded expressions.

const name = 'Alice'
const greeting = `Hello, ${name}!`
console.log(greeting) // Output: Hello, Alice!

Common String Methods

JavaScript provides a variety of methods to manipulate and interact with strings. Here are some of the most commonly used ones:

1. length: Returns the length of the string.

   const str = 'JavaScript'
   console.log(str.length) // Output: 10
   

2. toUpperCase(): Converts the string to uppercase.

   console.log(str.toUpperCase()) // Output: JAVASCRIPT
   

3. toLowerCase(): Converts the string to lowercase.

   console.log(str.toLowerCase()) // Output: javascript
   

4. indexOf(): Returns the index of the first occurrence of a substring.

   console.log(str.indexOf('Script')) // Output: 4
   

5. slice(): Extracts a section of the string and returns it as a new string.

   console.log(str.slice(0, 4)) // Output: Java
   

6. replace(): Replaces a substring with another substring.

   console.log(str.replace('Java', 'Type')) // Output: TypeScript
   

7. trim(): Removes whitespace from both ends of the string.

   const paddedStr = '   Hello, world!   '
   console.log(paddedStr.trim()) // Output: Hello, world!
   

8. split(): Splits the string into an array of substrings based on a delimiter.

   const sentence = 'JavaScript is awesome'
   console.log(sentence.split(' ')) // Output: ['JavaScript', 'is', 'awesome']
   

9. includes(): Checks if a string contains a specific substring.

   console.log(sentence.includes('awesome')) // Output: true
   

10. startsWith() and endsWith(): Check if a string starts or ends with a specific substring.

    console.log(sentence.startsWith('Java')) // Output: true
    console.log(sentence.endsWith('awesome')) // Output: true
    

Examples 🖥️

Example 1: Concatenating Strings

const firstName = 'John'
const lastName = 'Doe'

// Using the + operator
const fullName = firstName + ' ' + lastName
console.log(fullName) // Output: John Doe

// Using template literals
const fullNameTemplate = `${firstName} ${lastName}`
console.log(fullNameTemplate) // Output: John Doe