Implement Custom Reduce Function in JavaScript

Day 20/30 – Check if Object or Array is Empty in JavaScript Challenge 🧐 | JSON Logic 💻🚀 🧠 Problem: Given an object or array (from JSON.parse()), return whether it is empty. Rules: An empty object → has no key-value pairs An empty array → has no elements ✨ What this challenge teaches: Difference between objects vs arrays Understanding JSON structures Checking data safely before processing This logic is heavily used in: ⚡ API response validation ⚡ Form handling ⚡ Conditional rendering (React) ⚡ Backend data checks Test with: {} [] { name: "JS" } [1,2,3] Small logic — big real-world importance 💡 💬 How would you handle nested empty objects? #JavaScript #30DaysOfJavaScript #CodingChallenge #JSON #JSLogic #WebDevelopment #LearnToCode #CodeEveryday #DeveloperJourney #Programming #TechCommunity #LeetCode Check empty object JavaScript Check empty array JS JavaScript JSON validation JavaScript object methods LeetCode JavaScript solution JS interview questions Beginner JavaScript practice Daily coding challenge

📘 Day 65: JavaScript Arrays & Powerful Array Methods 🔹 Array Basics: • Similar to lists — store multiple values in one variable • Can hold different datatypes • Mutable, ordered, and allow duplicates • Written inside square brackets [ ] 🔹 Concat: • Combines multiple arrays • Keeps duplicate values 🔹 Spread Operator (...): • Modern way to merge arrays • Cleaner and more flexible than concat • Very important in real projects 🔹 Push & Pop: • push() → adds items to the end • pop() → removes last item 🔹 Shift & Unshift: • shift() → removes first item • unshift() → adds item at the start 🔹 Join: • Converts array into string • Separator can be customized 🔹 Sort: • Sorts alphabetically or numerically • Numbers are sorted before strings 🔹 Slice: • Extracts part of an array • Doesn’t change original array • Supports negative indexing 🔹 Splice (Important): • Insert, replace, or delete elements • Changes original array • Uses position, delete count, and new values 💡 Practiced how arrays make data handling easier and how these methods help in real-world JavaScript development. #Day65 #JavaScript #WebDevelopment #CodingJourney #FrontendDevelopment #LearningJavaScript #Arrays #JSBasics

Day 10/30 – JavaScript Once Function 🧠 | Ensure a Function Runs Only Once💻🚀 🧠 Problem: Given a function fn, return a new function that: Executes fn only once Returns the result on the first call Returns undefined on all subsequent calls ✨ This challenge helped me understand: Closures & state preservation Function wrappers How real-world features like one-time events, initialization logic, and API guards work This pattern is commonly used in: ⚡ Event listeners ⚡ Authentication flows ⚡ Performance optimization 💬 Where would you use a “run once” function? Comment below 👇 #JavaScript #30DaysOfJavaScript #CodingChallenge #Closures #JSLogic #LeetCode #WebDevelopment #LearnToCode #CodeEveryday #DeveloperJourney #Programming #TechCommunity JavaScript once function Call function only once JS JavaScript closures example Higher order functions JavaScript LeetCode JavaScript solution JS interview questions Beginner JavaScript practice Daily coding challenge

🧠 99% of JavaScript devs fall into this trap 👀 (Even with years of experience) No frameworks. No libraries. Just core JavaScript fundamentals. 🧩 Output-Based Question (parseInt + map) console.log(["1", "2", "3"].map(parseInt)); ❓ What will be printed? ❌ Don’t run the code 🧠 Think like the JavaScript engine A. [1, 2, 3] B. [1, NaN, NaN] C. [1, 2, NaN] D. Throws an error 👇 Drop ONE option in the comments Why this matters Most developers assume: parseInt only takes one argument map passes only the value Both assumptions are wrong. When fundamentals aren’t clear: bugs slip into production data parsing breaks silently debugging turns into guesswork Strong JavaScript developers don’t guess. They understand how functions are actually called. 💡 I’ll pin the full explanation after a few answers. #JavaScript #JSFundamentals #CodingInterview #WebDevelopment #FrontendDeveloper #FullStackDeveloper #DevelopersOfLinkedIn #DevCommunity #JavaScriptTricks #VibeCode

How to Master JavaScript 👇 ✨ Learn a bit of HTML & CSS 🧩 Variables & Data Types ➕ Operators 🔧 Functions 🔀 Conditionals (if/else) 🔁 Loops 📦 Arrays 🧱 Objects 🖱️ DOM Manipulation 🎯 Events 🚀 ES6+ Features ⏳ Async JavaScript (Promises, async/await) 🌐 Fetch & APIs ⚠️ Error Handling 📁 Modules 🐞 Debugging 💾 Browser Storage (localStorage, sessionStorage) 🏗️ OOP Basics ⚛️ Frameworks (React, Vue, etc.) 🛠️ Build Projects 🚀 #JavaScript #Coding #WebDevelopment #TechTips #ProgrammerLife #JavaScriptTutorial #FrontendDevelopment #WebDesign #LearnToCode #JavaScriptEssentials #CodeNewbie #TechEducation #WebDevCommunity #DevLife #DigitalSkills #SoftwareEngineering #JavaScriptNode #JSFrameworks #CodingForBeginners

Today I explored one of the most powerful and widely used concepts in JavaScript: Higher-Order Functions, along with the map, filter, and reduce array methods. Understanding higher-order functions helped me see how functions in JavaScript can be passed as arguments, returned from other functions, and used to write cleaner, more expressive code. The map, filter, and reduce methods showed how complex data transformations can be handled in a functional and readable way. What I learned: How higher-order functions enable reusable and composable logic Using map() to transform data without mutating the original array Using filter() to extract specific data based on conditions Using reduce() to accumulate values and solve complex problems in a single pass 💡 Key takeaway: These methods shift the focus from how to loop to what to compute, making code more declarative, readable, and maintainable. This session strengthened my ability to work with data efficiently and write cleaner JavaScript that scales well in real-world applications. #JavaScript #HigherOrderFunctions #MapFilterReduce #FunctionalProgramming #WebDevelopment #LearningJourney

Day 22/30 – Extend the Array Prototype in JavaScript Challenge 🧩 | Build array.last( ) 💻🚀 🧠 Problem: Enhance all arrays so that you can call: arr.last() Rules: Return the last element of the array If the array is empty → return -1 Assume array comes from JSON.parse() 🧠 Example : [1, 2, 3].last() // 3 [].last() // -1 💡 JavaScript Solution : Array.prototype.last = function() { if (this.length === 0) { return -1; } return this[this.length - 1]; }; 🔎 Why This Works Array.prototype lets us add methods to all arrays this refers to the current array instance this.length - 1 gives the last index Time Complexity: O(1) Space Complexity: O(1) ⚠️ Important Note In real production systems, modifying built-in prototypes is usually discouraged because it can: Cause conflicts Break third-party libraries Create unexpected behavior But for understanding JavaScript internals and interviews — this is GOLD 🔥 #JavaScript #30DaysOfJavaScript #CodingChallenge #Prototype #JSInternals #WebDevelopment #LearnToCode #Programming #DeveloperJourney #TechCommunity Extend Array prototype JavaScript JavaScript array last element JS prototype inheritance JavaScript interview questions Modify built-in objects JS Advanced JavaScript concepts

Day 64 – JavaScript String Methods Today I explored essential JavaScript String methods that help in manipulating and validating text data effectively. These methods are widely used in real-world applications such as form validation, data formatting, and UI handling. Topics Covered: length – Find the number of characters (including spaces) replace() – Replace the first occurrence of a specified value replaceAll() – Replace all matching values in a string split() – Convert a string into an array based on a separator indexOf() – Get the index position of a character or word slice() – Extract a portion of a string using index values trim() – Remove extra spaces from both ends trimStart() – Remove spaces from the beginning trimEnd() – Remove spaces from the end startsWith() – Check if a string starts with a specific value endsWith() – Check if a string ends with a specific value Understanding these methods makes string handling more efficient and improves code clarity and performance in JavaScript applications. #JavaScript #StringMethods #FrontendDevelopment #WebDevelopment #LearningJavaScript

🚀 JavaScript Tip: var vs let vs const — Explained Simply Understanding how variables work in JavaScript can save you from hard-to-debug issues later. Think of variables as containers that hold values ☕ 🔹 var – Old Style (Not Recommended) ➡️ Function scoped ➡️ Can be re-declared & reassigned ➡️ Gets hoisted → may cause unexpected bugs 👉 Use only if maintaining legacy code 🔹 let – Modern & Safe ➡️ Block scoped {} ➡️ Cannot be re-declared ➡️ Can be reassigned ➡️ Hoisted but protected by Temporal Dead Zone 👉 Best for values that change over time 🔹 const – Locked & Reliable ➡️ Block scoped {} ➡️ Cannot be re-declared or reassigned ➡️ Must be initialized immediately 👉 Best for fixed values and cleaner code ✅ Best Practice Use const by default, switch to let only when reassignment is needed, and avoid var 🚫 💡 Small fundamentals like these make a big difference in writing clean, scalable JavaScript. #JavaScript #WebDevelopment #FrontendDevelopment #ProgrammingTips #LearnJavaScript #CodingBestPractices #DeveloperLearning #SoftwareEngineering #100DaysOfCode

Today I solved a classic JavaScript problem: Removing duplicates from an array without using built-in methods like Set. Instead of relying on shortcuts, I implemented the logic manually using nested loops to fully understand how duplicate detection works internally. 🧠 Problem Given an array like: Copy code [1, 2, 2, 3, 4, 3] Return: [1, 2, 3, 4] 🔍 My Approach I created a new empty array called unique to store only distinct values. I looped through each element of the original array. For every element, I checked whether it already exists inside the unique array. If it does not exist, I pushed it into the unique array. If it already exists, I skipped it. This approach uses: An outer loop to iterate over the original array An inner loop to check for existing values A boolean flag (exists) to track duplicates 💡 Why I Chose This Approach While JavaScript provides a built-in way to remove duplicates using: [...new Set(arr)] I intentionally avoided it to: Strengthen my understanding of loops Improve my logical thinking Practice writing interview-style solutions Understand time complexity and algorithm behavior ⏱ Time Complexity O(n²) — because for each element, we may check the entire unique array. 🎯 Key Learning This problem helped me understand: Nested loop logic How duplicate detection works internally The importance of loop structure and placement Debugging mistakes like incorrect loop conditions Building strong fundamentals makes advanced concepts easier later. Consistency > shortcuts 💪 #JavaScript #ProblemSolving #WebDevelopment #100DaysOfCode #FrontendDeveloper #DSA #LearningInPublic