Mastering Functional Composition in JavaScript

So you want to write cleaner code in JavaScript - it's a game-changer. Functional composition is key. It's like building with Legos - you create these tiny functions that do one thing, and then you combine them to make something amazing. You define a function that takes multiple functions as arguments, and it returns a new function that applies the original functions in a specific order - it's pretty straightforward. It works. For example, you can create a `compose` function that takes multiple functions and returns a new function that applies them in a specific order - like this: ```javascript const compose = (...functions) => (x) => functions.reduceRight((acc, fn) => fn(acc), x); ``` And then you can use it to compose other functions, like `add2` and `multiply3`. It's simple: ```javascript const add2 = (num) => num + 2; const multiply3 = (num) => num * 3; const add2ThenMultiply3 = compose(multiply3, add2); console.log(add2ThenMultiply3(5)); // Output:``` But here's the thing - functional composition isn't just for synchronous functions. It also works with asynchronous functions, which is huge. You can create an `asyncCompose` function that takes multiple asynchronous functions and returns a new function that applies them in a specific order - like this: ```javascript const asyncCompose = (...fns) => (initialInput) => fns.reduceRight( (promise, fn) => promise.then(fn), Promise.resolve(initialInput) ); ``` And then you can use it to compose asynchronous functions, like `fetchData` and `transformData`. It's pretty cool: ```javascript const fetchData = (id) => new Promise((resolve) => { setTimeout(() => resolve(`Data for ${id}`), 1000); }); const transformData = (data) => `${data} transformed!`; const composedAsyncFunction = asyncCompose(transformData, fetchData); composedAsyncFunction(1).then(console.log); // Output after 1 second: "Data for 1 transformed!" ``` Now, to take it to the next level, you can use techniques like batching function calls and memoization. Memoization is like caching - it stores the results of expensive function calls so you don't have to repeat them. You can create a `memoize` function that takes a function and returns a new function that caches its results - like this: ```javascript const memoize = (fn) => { const cache = {}; return function (...args) { const key = JSON.stringify(args); if (!(key in cache)) { cache[key] = fn(...args); } return cache[key]; }; }; ``` It's a big deal. By using functional composition and these techniques, you can write more efficient and maintainable code in JavaScript - and that's what it's all about. Source: https://lnkd.in/g3-F4DKC #javascript #functionalprogramming #codingtips

⚡ JavaScript – Async JavaScript & APIs Handling Time-Consuming Tasks Efficiently JavaScript is single-threaded, but real applications need to handle: Server requests API calls Background operations Async JavaScript allows these tasks to run without blocking the UI. 🔹 What Is Asynchronous JavaScript? Asynchronous code runs in the background while the rest of the program continues. Examples: Fetching data from a server Reading files Timers (setTimeout) JavaScript handles this using callbacks, promises, and async/await. 🔹 Callbacks A callback is a function passed as an argument to another function, executed later. function getData(callback) { setTimeout(() => { callback("Data received"); }, 1000); } getData((data) => { console.log(data); }); 👉 Problem: Too many callbacks lead to callback hell 👉 Hard to read and maintain 🔹 Promises A Promise represents a value that will be available later. States of a Promise: Pending Fulfilled Rejected const promise = new Promise((resolve, reject) => { resolve("Success"); }); promise .then(result => console.log(result)) .catch(error => console.log(error)); 👉 Solves callback nesting 👉 Cleaner than callbacks 🔹 async / await A modern and cleaner way to handle promises. async function getData() { const result = await promise; console.log(result); } 👉 Looks like synchronous code 👉 Easier to read and debug 👉 Most used in modern JavaScript & React 🔹 Fetch API Used to request data from a server or API. fetch("https://lnkd.in/gBVe_Q-K") .then(response => response.json()) .then(data => console.log(data)) .catch(error => console.log(error)); Using async / await: async function fetchData() { const response = await fetch(url); const data = await response.json(); console.log(data); } 🔹 Working with APIs (Intro) APIs provide data from the backend, usually in JSON format. Used for: User data Product lists Dashboards Weather apps Frontend → consumes APIs Backend → provides APIs 🧠 Simple Way to Remember Callback → function runs later Promise → future value async / await → clean promise handling Fetch → get data from server API → bridge between frontend & backend ✅ Why Async JavaScript & APIs Matter Prevents UI freezing Essential for real-world applications Core concept for React, Node.js Frequently asked in interviews Without async code, apps feel slow. With async code, apps feel smooth. 🎯 Key Takeaway Async JavaScript & APIs prepare you for backend development and React. Master this, and you’re ready for real-world web applications 🚀 #JavaScript #AsyncJavaScript #APIs #WebDevelopment #FrontendDevelopment #Backend #LearningInPublic

Demystifying JavaScript Functions: The Complete Beginner's Guide 🧠 As a developer, understanding functions is like learning to walk in JavaScript—it's fundamental to everything you'll build. Let me break down every type of function in the simplest way possible! 1️⃣ Function Declaration (The Classic) The most basic way to define a function. Gets "hoisted" so you can call it before declaring it. ```javascript function greet(name) { return `Hello, ${name}!`; } console.log(greet('Sasi')); // Hello, Sasi! ``` 2️⃣ Function Expression (The Flexible) Assigning a function to a variable. More flexible but not hoisted. ```javascript const greet = function(name) { return `Hello, ${name}!`; }; ``` 3️⃣ Arrow Function (The Modern) ES6's concise syntax. Perfect for callbacks and one-liners! ```javascript const greet = (name) => `Hello, ${name}!`; // Single parameter? No parentheses needed! const square = x => x * x; ``` 4️⃣ IIFE (Immediately Invoked) Runs immediately after definition. Great for isolated scopes. ```javascript (function() { console.log('I run immediately!'); })(); ``` 5️⃣ Higher-Order Functions (The Smart Ones) Functions that take other functions as arguments or return them. ```javascript // map() is a higher-order function const numbers = [1, 2, 3]; const doubled = numbers.map(x => x * 2); ``` 6️⃣ Generator Functions (The Pausable) Can pause execution and resume later. Use function* and yield. ```javascript function* countUp() { let count = 0; while (true) { yield count++; } } ``` 7️⃣ Async Functions (The Patient) Simplify working with promises using async/await. ```javascript async function fetchData() { const response = await fetch('url'); const data = await response.json(); return data; } ``` 🔄 Function Types Quick Guide: · Regular functions: Your all-purpose workhorse · Arrow functions: Short, clean, no this binding · Async functions: Handle promises elegantly · Generator functions: Control execution flow · IIFEs: Run once, protect scope · Higher-order: Treat functions as data 🎯 When to Use What: · Need this binding? → Regular functions · Writing callbacks? → Arrow functions · Working with APIs? → Async functions · Need reusable logic? → Function expressions · Want clean, modern code? → Arrow functions 💡 Pro Tip: Arrow functions don't have their own this context—they inherit it from the parent scope. Regular functions do have their own this. --- Let's Discuss! 👇 · Which function type do you use most often? · What's your favorite "aha!" moment with JavaScript functions? 🔥 Want more practical insights like this? ✅ Follow Sasikumar S for daily JavaScript tips ✅ Like & Repost to help other developers ✅ Comment your function questions below! #JavaScript #WebDevelopment #Programming #Coding #Frontend #Developer #WebDev #Tech #SoftwareEngineering #LearnToCode #ProgrammingTips #CodeNewbie #JavaScriptTips #Functions #ES6 #AsyncJavaScript

So you wanna build a JavaScript code analyzer. It's a great idea. This thing can help you identify issues in your code before it's even executed. You'll learn how to create a custom static analysis tool that manipulates the Abstract Syntax Tree (AST) - and trust me, it's a game-changer. Here's the lowdown: there are a few key components to focus on. Lexical analysis, for instance, is all about breaking down source code into tokens - think of it like taking apart a sentence into individual words. Then there's parsing, which converts those tokens into an AST - it's like creating a map of your code's structure. After that, you've got static analysis, where you implement custom rules to identify potential issues - like a referee in a game, but for your code. And finally, there's reporting, where you send the results back to the developer - kind of like a report card, but for your code's performance. Now, let's say you wanna build a simple JavaScript static analyzer using Node.js. You can use Acorn to parse JavaScript code into an AST - it's a solid choice. Then, you define a visitor function to traverse the AST and look for specific patterns, like console.log statements. But things can get complicated - like when you're dealing with conditional console logging, or using Babel for ES6+ support. You've got to track variable scopes and function declarations, and leverage Babel's parsing functionality alongside Acorn. And don't even get me started on handling minified code - you'll need to integrate source maps to connect the minified code back to its original context. To make your analysis more efficient, consider using incremental analysis - only analyze files that have changed. It's like focusing on the most important tasks first. You can also use parallel processing to analyze multiple files at the same time - it's like having multiple workers on the job. And with selective rule application, you can allow users to choose which rules are active - it's like giving them a customized experience. You've got options, too - you can use existing tools like ESLint, or build a custom analyzer from scratch. Or, you can build plugins for existing tools to get the best of both worlds - the power of community tools, plus bespoke rules. Real-world use cases include code quality enforcement in CI/CD pipelines, security auditing, and refactoring assistance - it's like having a personal assistant for your code. But what if things go wrong? To diagnose issues in your static analyzer, try using AST visualization - it's like looking at a map of your code's structure. Implement verbose logging to get more detailed information - it's like having a detailed report of what's going on. Create comprehensive unit tests for each static analysis rule - it's like testing each part of your analyzer to make sure it's working correctly. And regularly benchmark

🚀 How JavaScript Actually Works — In Depth (Execution Context, Call Stack & More). Let’s break it down step by step. 🔹 1. JavaScript Is Single-Threaded — But Asynchronous JavaScript has: • One main thread • One Call Stack • But it can still handle asynchronous operations efficiently This is possible because of the JavaScript Runtime Environment, which includes: • Call Stack • Heap Memory • Web APIs (in browsers) • Callback Queue • Microtask Queue • Event Loop 🔹 2. Global Execution Context (GEC) Is Created First When your JavaScript file starts running, the very first thing created is the Global Execution Context, which has two phases: ✅ Phase 1 — Memory Creation (Hoisting Phase) JavaScript scans the entire code and allocates memory for: • Variables → stored as undefined • Functions → stored with full function definition Example: console.log(name); var name = "Raj"; function greet() { console.log("Hello"); } During memory phase: • name → allocated as undefined • greet → stored as actual function This is why console.log(name) prints undefined and not an error. 🔹 3. Phase 2 — Code Execution Phase Now JavaScript starts executing line by line. • console.log(name) → prints undefined • Then name = "Raj" is assigned • Functions execute only when called 🔹 4. Function Execution Context (FEC) Whenever a function is called, a new Execution Context is created on top of the Call Stack. Example: function add(a, b) { return a + b; } add(5, 10); Steps: Global Execution Context exists add(5,10) is called New Execution Context for add() is created It has: • Its own memory space • Its own variables • Its own return value Once the function finishes, its execution context is removed from the Call Stack. 🔹 5. Call Stack — The Heart of JavaScript Execution The Call Stack follows LIFO (Last In, First Out). Example: function first() { second(); } function second() { third(); } function third() { console.log("Done"); } first(); Call Stack Flow: • first() pushed • second() pushed • third() pushed • third() completes → popped • second() completes → popped • first() completes → popped 🔹 6. How Asynchronous Code Runs (Event Loop) Example: console.log("Start"); setTimeout(() => { console.log("Inside Timeout"); }, 0); console.log("End"); Execution Order: "Start" prints setTimeout goes to Web APIs "End" prints Callback goes to Callback Queue Event Loop moves it to Call Stack "Inside Timeout" prints Even with 0ms, it runs after synchronous code. 🔹 7. Microtasks vs Macrotasks Microtasks (higher priority): • Promises • MutationObserver Macrotasks: • setTimeout • setInterval Example: console.log("A"); setTimeout(() => console.log("B"), 0); Promise.resolve().then(() => console.log("C")); console.log("D"); Output: A D C B Because Microtasks run before Macrotasks. #JavaScript #WebDevelopment #Frontend #NodeJS #EventLoop #ExecutionContext #SoftwareEngineering #Programming #JSMastery

🌟 10 Useful JavaScript Snippets You Might Not Know Quick, practical JS helpers that can save time and clean up your code! 💡 --- 1️⃣ Randomize an array (Fisher-Yates shuffle) ```javascript const shuffleArray = (arr) => arr.sort(() => Math.random() - 0.5); console.log(shuffleArray([1, 2, 3, 4, 5])); ``` 2️⃣ Flatten nested arrays ```javascript const flatten = (arr) => [].concat(...arr); console.log(flatten([1, [2, 3], [4, [5]]])); ``` 3️⃣ Check if an object is empty ```javascript const isEmpty = (obj) => Object.keys(obj).length === 0; console.log(isEmpty({})); // true ``` 4️⃣ Remove duplicates from an array ```javascript const unique = (arr) => [...new Set(arr)]; console.log(unique([1, 2, 2, 3, 3, 4])); ``` 5️⃣ Get current date in YYYY-MM-DD format ```javascript const today = () => new Date().toISOString().slice(0, 10); console.log(today()); ``` 6️⃣ Capitalize the first letter of a string ```javascript const capitalize = (str) => str.charAt(0).toUpperCase() + str.slice(1); console.log(capitalize("hello world")); ``` 7️⃣ Convert RGB to Hex ```javascript const rgbToHex = (r, g, b) => "#" + ((1 << 24) + (r << 16) + (g << 8) + b).toString(16).slice(1); console.log(rgbToHex(255, 100, 50)); ``` 8️⃣ Wait/delay function ```javascript const delay = (ms) => new Promise(resolve => setTimeout(resolve, ms)); await delay(2000); // waits 2 seconds ``` 9️⃣ Copy text to clipboard ```javascript const copyToClipboard = (text) => navigator.clipboard.writeText(text); copyToClipboard("Hello, devs! 👨💻"); ``` 🔟 Extract parameters from URL ```javascript const getParams = (url) => Object.fromEntries(new URL(url).searchParams); console.log(getParams('https://lnkd.in/g3Y-T5jw')); ``` --- 📌 Which snippet did you find most useful? Have a better version? Share below! 👇 --- 📌 Follow Sasikumar S for more hands-on developer content ❤️ Join skAI – Daily Developer Learning Community for daily tips, growth hacks & career opportunities 💌 Repost to help others in your network 🤝 Connect: sasiias2024@gmail.com 💟 Explore more: sk-techland.web.app #JavaScript #WebDevelopment #CodingTips #JS #DeveloperTools #Programming #CodeSnippets #TechTips #Frontend #LearnToCode

In a Javascript L1 & L2 round the following questions can be asked from interviewer. 1. What is the difference between 'Pass by Value' and 'Pass by Reference'? 2. What is the difference between map and filter ? 3. What is the difference between map() and forEach() 4. What is the difference between Pure and Impure functions? 5. What is the difference between for-in and for-of ? 6. What are the differences between call(), apply() and bind() ? 7. List out some key features of ES6 ? 8. What’s the spread operator in javascript ? 9. What is rest operator in javascript ? 10. What are DRY, KISS, YAGNI, SOLID Principles ? 11. What is temporal dead zone ? 12. Different ways to create object in javascript ? 13. Whats the difference between Object.keys,values and entries 14. Whats the difference between Object.freeze() vs Object.seal() 15. What is a polyfill in javascript ? 16. What is generator function in javascript ? 17. What is prototype in javascript ? 18. What is IIFE ? 19. What is CORS ? 20. What are the different datatypes in javascript ? 21. What are the difference between typescript and javascript ? 22. What is authentication vs authorization ? 23. Difference between null and undefined ? 24. What is the output of 3+2+”7” ? 25. Slice vs Splice in javascript ? 26. What is destructuring ? 27. What is setTimeOut in javascript ? 28. What is setInterval in javascript ? 29. What are Promises in javascript ? 30. What is a callstack in javascript ? 31. What is a closure ? 32. What are callbacks in javascript ? 33. What are Higher Order Functions in javascript ? 34. What is the difference between == and === in javascript ? 35. Is javascript a dynamically typed language or a statically typed language 36. What is the difference between Indexeddb and sessionstorage ? 37. What are Interceptors ? 38. What is Hoisting ? 39. What are the differences let, var and const ? 41. Differences between Promise.all, allSettled, any, race ? 42. What are limitations of arrow functions? 43. What is difference between find vs findIndex ? 44. What is tree shaking in javascrip 45. What is the main difference between Local Storage and Session storage 46. What is eval() 47. What is the difference between Shallow copy and deep copy 48. What are the difference between undeclared and undefined variables 49. What is event bubbling 50. What is event capturing 51. What are cookies 52. typeOf operator 53. What is this in javascript and How it behaves in various scenarios 54. How do you optimize the performance of application 55. What is meant by debouncing and throttling 𝐠𝐞𝐭 𝐞𝐛𝐨𝐨𝐤 𝐰𝐢𝐭𝐡 (detailed 232 ques = 90+ frequently asked Javascript interview questions and answers, 90+ Reactjs Frequent Ques & Answers, 50+ Output based ques & ans, 23+ Coding Questions & ans, 2 Machine coding ques & ans) 𝐄𝐛𝐨𝐨𝐤 𝐋𝐢𝐧𝐤: https://lnkd.in/gJMmH-PF Follow on Instagram : https://lnkd.in/gXTrcaKP #javascriptdeveloper #reactjs #reactnative #vuejsdeveloper #angular #angulardeveloper

JavaScript Fundamentals - Part 1 JavaScript Runtime - environment in which JS code runs It is made up of: - JavaScript engine - Browser capabilities - Browser Web APIs - Queues - Event loop JS is itself is: - Single-threaded - Synchronous by default Asynchronous behavior comes from the browser runtime, not from JavaScript itself. JavaScript Engine It is responsible for executing JS code. Ex: V8(for Chrome), Spider Monkey(for Firerfox) It contains 2 main components: Memory Heap - Stores variables, objects and functions Call Stack - Executes JS code - Follows Last In, First Out order - Only one piece of code executes at a time Call Stack Execution The call stack manages function execution order. Example function a(){ b(); } function b(){ console.log("Hello"); } a(); Execution flow: - a() is pushed onto stack - b() is pushed onto stack - console.log() executes - functions complete and are popped off the stack If the call stack is blocked, no other JS code can execute. Browsers provide additional capabilities to JS through Web APIs which are: setTimeout, setInterval, fetch, DOM events, Geolocation, Web Storage So all asynchronous work moved to these Web APIs and continues execution. Example: setTimeout(() => { console.log("Hello"); },1000); Execution flow: - JS registers the timer - Browser Web API handles the timer - JS continues running without waiting Task Queues: Microtask Queue it has: Promise.then, async/await, MutationObeserver(it provides ability to watch for changes being made to the DOM tree and execute specified callback function when those changes occur) Macrotask Queue is an lower priority queue and contains: setTimeout, setInterval, DOM events Microtasks are always executed before macrotasks. Event loop continuously checks the call stack and queues and its execution order: - Call stack must be empty - Execute all microtasks - Execute one macrotask - Repeat the cycle so based on the above explanation, let me know the output of below snippet with execution order. console.log("A"); setTimeout(() => { console.log("B"); },0); Promise.resolve().then(() => { console.log("C"); }); console.log("D"); Please follow for Part 2 updates. 👍 #javascriptfundamentals #uideveloper #corejs

JavaScript fundamentals - Part 2 Execution context - it is an environment in which JS code is executed. Every time JS runs code, it does so inside an execution context. At any moment: - Only one execution context is active. - It always sits on top of the Call Stack Types of Execution Context - Global Execution Context(GEC) - Function Execution Context(FEC) What is Global Execution Context ? - Created once when the JS file starts executing. - Represents code not inside any function - Sits at the bottom of the call stack GEC contains 2 phases 1) Memory Creation Phase - it allocates memory and set up the scope During this phase: - var variables -> initialized as undefined - function declarations -> fully hoisted - let & const -> allocated but not initialized - this -> points to global object(window) 2) Code Execution Phase - JS code executes line by line - Variables get values - Functions are called Example var a = 10; function foo(){ console.log("Hello"); } foo(); const test = () = { console.log("test"); } test(); Memory creation phase: a -> undefined foo -> function reference Execution phase a -> 10 foo() is called function greetings() { console.log("Greetings"); sayHi(); } function sayHi() { console.log("Hi"); } greetings(); What is Function Execution Context? - Created every time function is called - Each function call gets new execution context - Pushed onto the call stack - Destroyed after function finishes execution What does FEC contain? - Memory creation phase: > function arguments are assigned > local variables are allocated > inner function declarations are hoisted > this is determined - Code Execution Phase: > function body executes line by line > values are assigned > nested function calls create more execution contexts function add(x, y) { var result = x + y; return result; } add(2,3); Inside add execution context: x -> 2 y -> 3 result -> undefined(creation phase) result -> 5(execution phase) So, based on above explanation, what is the Call Stack flow: function one() { two(); } function two() { three(); } function three() { console.log("Done"); } one(); Please follow for Part 3 updates. 👍 #javascriptfundamentals #uideveloper #corejs

So, you think you know JavaScript objects inside and out. But, let's get real - do you really understand how they inherit properties? It's like trying to find a specific book in a huge library, you gotta know where to look. JavaScript's secret sauce is prototypes. Every object has this internal prototype link that's like a map to its ancestors. When you try to access a property, JavaScript goes on a search mission through the prototype chain - it's like following a trail of breadcrumbs. Here's the lowdown: you try to access a property on an object, and if it's there, you get its value, no big deal. But, if it's not, JavaScript checks the object's prototype, and if it's not there, it keeps searching until it finds the property or hits a dead end. It's kinda like when you're trying to remember where you put your keys - you check the usual spots, and if you still can't find them, you start searching everywhere else. Simple. Now, let's dive deeper - the prototype chain is like a family tree, where each object inherits properties from its parent. And, just like in real life, the properties you inherit from your parents are shared with your siblings, but the ones you own are unique to you. For example, take a look at this code: ```javascript const animal = { eats: true, walk: function() { console.log('Animal walks'); } }; const rabbit = { jumps: true }; Object.setPrototypeOf(rabbit, animal); console.log(rabbit.jumps); // true console.log(rabbit.eats); // true rabbit.walk(); // "Animal walks" ``` In this example, the `rabbit` object inherits properties from the `animal` object - it's like the `rabbit` is saying, "Hey, I've got a parent who can teach me some cool stuff." And, here's the thing - methods on the prototype are shared across all instances, like a family recipe that's passed down through generations. But, properties on the instance are unique to each object, like a personal journal that's just for you. Oh, and one more thing - `__proto__` points to the object's prototype, like a sign that says, "Hey, my parent is over here." And, `prototype` is on constructor functions, like a blueprint for building a house. Now, you might be wondering about ES6 classes - they're like a fancy new car that's actually just a redesigned old model. They're syntactic sugar over constructor functions and prototypes, making it easier to create objects that inherit properties. And, if you're into React, you should know that class components use prototypes, but functional components don't - it's like the difference between a big, fancy restaurant and a food truck. Source: https://lnkd.in/ghnuf2BC #JavaScript #Prototypes #Inheritance #Coding