Date and Time Utilities

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
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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 Validate An Email Address

Basic email validation.

Output

JavaScript Program to Display Date and Time
Print current date/time.
Output
JavaScript Program to Format the Date
Format with locale options.
Output
Javascript Program to Display Current Date
Use toLocaleDateString.
Output
JavaScript Program to Compare The Value of Two Dates
Compare timestamps.
Output
JavaScript Program to Create Countdown Timer
Simple countdown.
Output
JavaScript Program to Pass Parameter to a setTimeout() Function
Pass args to setTimeout.
Output
JavaScript Program to Find ASCII Value of Character
Use charCodeAt.
Output
Keep Practicing
Use the online compiler to run examples and test variations. Reinforce learning by building small scripts for each topic.
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.