String Utilities and Text Processing

Key takeaway: Practice JavaScript with 102+ runnable code examples — variables, arrays, strings, objects, math, dates, and DOM — all with expected output to verify instantly.

JavaScript is a programming language that makes web pages interactive. These examples are for front-end developers, bootcamp students, self-taught coders, and anyone preparing for JS interviews.

Last updated: August 2026 · 102 examples

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Who is this for: Front-end developers, bootcamp students, interview candidates, and self-taught coders building JavaScript skills. Use this when: you need quick reference code, want to practice for interviews, or learn JS concepts hands-on.

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Topics
JavaScript Program To Print Hello WorldJavaScript Program to Add Two NumbersJavaScript Program to Find the Square RootJavaScript Program to Calculate the Area of a TriangleJavaScript Program to Swap Two VariablesJavaScript Program to Solve Quadratic EquationJavaScript Program to Convert Kilometers to MilesJavascript Program to Convert Celsius to FahrenheitJavascript Program to Generate a Random NumberJavascript Program to Check if a number is Positive, Negative, or ZeroJavascript Program to Check if a Number is Odd or EvenJavaScript Program to Find the Largest Among Three NumbersJavaScript Program to Check Prime NumberJavaScript Program to Print All Prime Numbers in an IntervalJavaScript Program to Find the Factorial of a NumberJavaScript Program to Display the Multiplication TableJavaScript Program to Print the Fibonacci SequenceJavaScript Program to Check Armstrong NumberJavaScript Program to Find Armstrong Number in an IntervalJavaScript Program to Make a Simple CalculatorJavaScript Program to Find the Sum of Natural NumbersJavaScript Program to Check if the Numbers Have Same Last DigitJavaScript Program to Find HCF or GCDJavaScript Program to Find LCMJavaScript Program to Find the Factors of a NumberJavaScript Program to Find Sum of Natural Numbers Using RecursionJavaScript Program to Guess a Random NumberJavaScript Program to Shuffle Deck of CardsJavaScript Program to Display Fibonacci Sequence Using RecursionJavaScript Program to Find Factorial of Number Using RecursionJavaScript Program to Convert Decimal to BinaryJavaScript Program to Find ASCII Value of CharacterJavaScript Program to Check Whether a String is Palindrome or NotJavaScript Program to Sort Words in Alphabetical OrderJavaScript Program to Replace Characters of a StringJavaScript Program to Reverse a StringJavaScript Program to Create Objects in Different WaysJavaScript Program to Check the Number of Occurrences of a Character in the StringJavaScript Program to Convert the First Letter of a String into UpperCaseJavaScript Program to Count the Number of Vowels in a StringJavaScript Program to Remove a Property from an ObjectJavaScript Program to Check Whether a String Starts and Ends With Certain CharactersJavaScript Program to Check if a Key Exists in an ObjectJavaScript Program to Clone a JS ObjectJavaScript Program to Loop Through an ObjectJavaScript Program to Merge Property of Two ObjectsJavaScript Program to Count the Number of Keys/Properties in an ObjectJavaScript Program to Add Key/Value Pair to an ObjectJavaScript Program to Replace All Occurrences of a StringJavaScript Program to Create Multiline StringsJavaScript Program to Format Numbers as Currency StringsJavaScript Program to Generate Random StringJavaScript Program to Check if a String Starts With Another StringJavaScript Program to Trim a StringJavaScript Program to Convert Objects to StringsJavaScript Program to Check Whether a String Contains a SubstringJavaScript Program to Compare Two StringsJavaScript Program to Encode a String to Base64JavaScript Program to Replace all Instances of a Character in a StringJavaScript Program to Replace All Line Breaks withJavaScript Program to Display Date and TimeJavaScript Program to Check Leap YearJavaScript Program to Format the DateJavascript Program to Display Current DateJavaScript Program to Compare The Value of Two DatesJavaScript Program to Create Countdown TimerJavaScript Program to Remove Specific Item From an ArrayJavaScript Program to Check if An Array Contains a Specified ValueJavaScript Program to Insert Item in an ArrayJavaScript Program to Append an Object to an ArrayJavaScript Program to Check if An Object is An ArrayJavaScript Program to Empty an ArrayJavaScript Program to Add Element to Start of an ArrayJavaScript Program to Remove Duplicates From ArrayJavaScript Program to Merge Two Arrays and Remove Duplicate ItemsJavaScript Program to Sort Array of Objects by Property ValuesJavaScript Program to Create Two Dimensional ArrayJavaScript Program to Extract Given Property Values from Objects as ArrayJavaScript Program to Compare Elements of Two ArraysJavaScript Program to Get Random Item From an ArrayJavaScript Program To Perform Intersection Between Two ArraysJavaScript Program to Split Array into Smaller ChunksJavaScript Program to Include a JS file in Another JS fileJavaScript Program to Get File ExtensionJavaScript Program To Check If A Variable Is undefined or nullJavaScript Program to Set a Default Parameter Value For a FunctionJavaScript Program to Illustrate Different Set OperationsJavascript Program to Generate a Random Number Between Two NumbersJavaScript Program To Get The Current URLJavaScript Program to Validate An Email AddressJavaScript Program to Check If a Variable is of Function TypeJavaScript Program To Work With ConstantsJavaScript Program to Pass Parameter to a setTimeout() FunctionJavaScript Program to Generate a Range of Numbers and CharactersJavaScript Program to Perform Function OverloadingJavaScript Program to Implement a StackJavaScript Program to Implement a QueueJavaScript Program to Check if a Number is Float or IntegerJavaScript Program to Pass a Function as ParameterJavaScript Program to Get the Dimensions of an ImageJavaScript Program to Remove All Whitespaces From a TextJavaScript Program to Write to Console
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JavaScript Program to Compare Two Strings

Use localeCompare.

Output

JavaScript Program to Check Whether a String is Palindrome or Not
Compare reversed string.
Output
JavaScript Program to Replace Characters of a String
Replace chars using regex.
Output
JavaScript Program to Reverse a String
Reverse a string.
Output
JavaScript Program to Convert the First Letter of a String into UpperCase
Capitalize first letter.
Output
JavaScript Program to Count the Number of Vowels in a String
Use regex to count.
Output
JavaScript Program to Replace All Occurrences of a String
Use replaceAll.
Output
JavaScript Program to Create Multiline Strings
Use template literals.
Output
JavaScript Program to Generate Random String
Pick random chars.
Output
JavaScript Program to Trim a String
Remove surrounding whitespace.
Output
JavaScript Program to Convert Objects to Strings
Use JSON.stringify.
Output
JavaScript Program to Check Whether a String Contains a Substring
Use includes.
Output
JavaScript Program to Encode a String to Base64
Use btoa.
Output
JavaScript Program to Replace all Instances of a Character in a String
Use replaceAll.
Output
JavaScript Program to Replace All Line Breaks with
Replace \n with space.
Output
Keep Practicing
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FAQ
Yes, run them instantly. Copy the code into our online JS compiler or your browser console (F12 → Console). Output uses console.log.
ES6+ (modern JavaScript). All examples work in Chrome, Firefox, Safari, and Edge. Arrow functions, template literals, and destructuring are used where appropriate.
Yes, absolutely. All examples are free to copy, modify, and share. Experimentation is the fastest way to learn JavaScript.
Start with basics, then build up. Begin with Hello World → variables → arithmetic → control flow → functions → strings → arrays → objects.
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.