Do I need ES6 features to follow these examples?

Most examples use core syntax supported by modern browsers. ES6 features are noted where used.

Can I modify and share these examples?

Yes. These are for learning—copy, tweak, and share your variations for practice.

Where should beginners start?

Begin with Hello World, variables, arithmetic, then progress to control flow, functions, strings, and arrays.

String Utilities and Text Processing

Work with strings—palindrome checks, vowel counting, trimming, replacing characters, formatting, and Base64 encoding. Learn practical text processing patterns that appear in everyday tasks.

Try JavaScript Compiler

JavaScript Program to Replace all Instances of a Character in a String

Use replaceAll.

console.log("balloon".replaceAll("l","x"));

Output

JavaScript Program to Check Whether a String is Palindrome or Not

Compare reversed string.

                          function isPal(s){const t=s.toLowerCase().replace(/[^a-z0-9]/g,""); return t===t.split("").reverse().join("");} console.log(isPal("Racecar"));
                        

Output

JavaScript Program to Replace Characters of a String

Replace chars using regex.

const s="hello"; console.log(s.replace(/l/g,"x"));

Output

JavaScript Program to Reverse a String

Reverse a string.

const s="JavaScript"; console.log(s.split("").reverse().join(""));

Output

JavaScript Program to Convert the First Letter of a String into UpperCase

Capitalize first letter.

                          function cap(s){return s.charAt(0).toUpperCase()+s.slice(1);} console.log(cap("hello"));
                        

Output

JavaScript Program to Count the Number of Vowels in a String

Use regex to count.

                          function vowels(s){const m=s.match(/[aeiou]/gi); return m? m.length:0;} console.log(vowels("Hello World"));
                        

Output

JavaScript Program to Replace All Occurrences of a String

Use replaceAll.

const s="a a a"; console.log(s.replaceAll("a","b"));

Output

JavaScript Program to Create Multiline Strings

Use template literals.

const s=`line1\nline2`; console.log(s);

Output

JavaScript Program to Generate Random String

Pick random chars.

                          const chars="abcdefghijklmnopqrstuvwxyz0123456789"; let s=""; for(let i=0;i<8;i++){s+=chars[Math.floor(Math.random()*chars.length)];} console.log(s);
                        

Output

JavaScript Program to Trim a String

Remove surrounding whitespace.

console.log("  hello  ".trim());

Output

JavaScript Program to Convert Objects to Strings

Use JSON.stringify.

const o={a:1}; console.log(JSON.stringify(o));

Output

JavaScript Program to Check Whether a String Contains a Substring

Use includes.

console.log("hello world".includes("world"));

Output

JavaScript Program to Compare Two Strings

Use localeCompare.

console.log("apple".localeCompare("banana"));

Output

JavaScript Program to Encode a String to Base64

Use btoa.

console.log(btoa("hello"));

Output

JavaScript Program to Replace All Line Breaks with

Replace \n with space.

const s="a\nb\nc"; console.log(s.replace(/\r?\n/g," "));

Output

Keep Practicing

Use the online compiler to run examples and test variations. Reinforce learning by building small scripts for each topic.

FAQ

Yes. You can copy the code into the JavaScript compiler page or your browser console to see the output. Some examples use console.log to print results.

Most examples use foundational syntax available in modern browsers. Where templates or arrow functions are used, they follow ES6 conventions widely supported today.

Absolutely. These examples are provided for learning. Copy, tweak values, and experiment to understand how the logic changes.

Start with Hello World, variables, and arithmetic. Then try control flow, functions, strings, and arrays to build confidence.

Learn JavaScript by Practicing Examples

Hands-on practice is the fastest way to understand JavaScript. Each example above focuses on a single concept—from strings, arrays, and objects to math utilities, dates, loops, and functions. Try editing variables, adding conditions, or refactoring logic, then observe the output changes instantly.

Use our tools to deepen your learning: JavaScript Compiler to run snippets, and the JavaScript Tutorial for guided theory and practice.

Beginner-Friendly

Start with variables, operators, and control flow. Build confidence with simple, readable programs.

Practical Patterns

Practice common tasks like formatting strings, manipulating arrays, and working with dates.

Grow Skills

Advance to objects, classes, and asynchronous patterns such as promises and async/await.

String Utilities and Text Processing

JavaScript Program to Replace all Instances of a Character in a String

Output

JavaScript Program to Check Whether a String is Palindrome or Not

Output

JavaScript Program to Replace Characters of a String

Output

JavaScript Program to Reverse a String

Output

JavaScript Program to Convert the First Letter of a String into UpperCase

Output

JavaScript Program to Count the Number of Vowels in a String

Output

JavaScript Program to Replace All Occurrences of a String

Output

JavaScript Program to Create Multiline Strings

Output

JavaScript Program to Generate Random String

Output

JavaScript Program to Trim a String

Output

JavaScript Program to Convert Objects to Strings

Output

JavaScript Program to Check Whether a String Contains a Substring

Output

JavaScript Program to Compare Two Strings

Output

JavaScript Program to Encode a String to Base64

Output

JavaScript Program to Replace All Line Breaks with

Output

Keep Practicing

FAQ

Can I run these examples in the browser?

Do I need ES6 features to follow these examples?

Can I copy and modify the examples?

Where should beginners start?

Learn JavaScript by Practicing Examples

Beginner-Friendly

Practical Patterns

Grow Skills