13 September 2025

#Javascript

#Javascript

Key Concepts


S.No Topic Sub-Topics
1Introduction to JavaScriptHistory of JavaScript, Features, Uses, JS vs Java, JS engines
2JavaScript BasicsVariables, Data types, Operators, Expressions, Statements
3Control StructuresIf-else, Switch-case, For loop, While loop, Do-while loop
4FunctionsFunction declaration, Function expression, Arrow functions, Parameters, Return values
5Scope & HoistingGlobal scope, Local scope, Block scope, var vs let vs const, Hoisting behavior
6Objects & ArraysObject literals, Properties & methods, Arrays, Array methods, Nested objects
7ES6 FeaturesLet & Const, Template literals, Destructuring, Default parameters, Spread & Rest operators
8Strings & String MethodsString properties, Concatenation, Template literals, Common string methods, String manipulation
9Numbers & MathNumber types, Math object, Number methods, Parsing, Random numbers
10Date & TimeDate object, Creating dates, Methods, Formatting dates, Date arithmetic
11DOM ManipulationDocument object, getElementById, querySelector, Changing content, Adding/removing elements
12EventsEvent types, addEventListener, Event object, Event bubbling, Event delegation
13JavaScript BOMWindow object, Location, History, Navigator, Timers (setTimeout, setInterval)
14JavaScript FormsForm elements, Accessing values, Validation, Form submission, Prevent default
15JavaScript Arrays AdvancedArray iteration, map, filter, reduce, find, some & every, sort & reverse
16Objects AdvancedObject methods, Object.keys, Object.values, Object.entries, Object.assign, Prototypes
17ES6 ClassesClass syntax, Constructor, Methods, Inheritance, Static methods, Getters & Setters
18ModulesExport, Import, Named export, Default export, Using modules in browser & Node.js
19Promises & Async/AwaitPromise syntax, then & catch, Chaining promises, Async functions, Await keyword
20Fetch APIGET request, POST request, Handling JSON, Error handling, Async/await integration
21JavaScript Error Handlingtry-catch-finally, Throwing errors, Error types, Custom errors, Debugging techniques
22JavaScript Regular ExpressionsRegExp syntax, Patterns, Testing, Matching, Replacing, Flags
23JavaScript ClosuresDefinition, Lexical scope, Use cases, Private variables, Practical examples
24JavaScript CallbacksCallback functions, Asynchronous callbacks, Callback hell, Error-first callbacks, Best practices
25JavaScript Higher-Order FunctionsDefinition, map, filter, reduce, forEach, Practical examples
26JavaScript Event LoopCall stack, Web APIs, Callback queue, Microtasks, Macrotasks, Understanding async behavior
27JavaScript Memory ManagementGarbage collection, Memory leaks, Closures & memory, Best practices, Profiling memory
28JavaScript Design PatternsModule pattern, Singleton pattern, Observer pattern, Factory pattern, Revealing module pattern
29JavaScript TestingUnit testing, Jest framework, Mocha & Chai, Testing DOM, Mocking functions
30Hands-on ProjectCreate interactive web app, DOM manipulation, Event handling, Fetch API integration, Form validation

Interview question

Basic Level

  1. What is JavaScript?
  2. Difference between Java and JavaScript?
  3. What are the data types in JavaScript?
  4. Difference between let, var, and const?
  5. What is hoisting?
  6. What is scope?
  7. What is an arrow function?
  8. Difference between == and ===?
  9. What are template literals?
  10. Difference between null and undefined?
  11. What is the typeof operator?
  12. What is JSON?
  13. What is a callback function?
  14. What is an array?
  15. What is an object?
  16. What is the spread operator?
  17. What is event bubbling?
  18. What is event capturing?
  19. What is "use strict"?
  20. What is DOM?
  21. What is type coercion?
  22. What are primitive and non-primitive data types?
  23. Difference between ++i and i++?
  24. What is console.log() used for?
  25. What are higher-order functions?

Intermediate Level

  1. What is a promise?
  2. What are async/await?
  3. What is the event loop?
  4. What is the call stack?
  5. What is closure?
  6. What is a prototype?
  7. What is prototypal inheritance?
  8. What is destructuring?
  9. What is currying?
  10. Difference between synchronous and asynchronous?
  11. What are modules in JavaScript?
  12. What is this keyword?
  13. How does binding work?
  14. Difference between slice and splice?
  15. What are pure functions?
  16. What is immutability?
  17. What is a generator function?
  18. What is a symbol?
  19. What are Maps and Sets?
  20. What is debouncing?
  21. What is throttling?
  22. What is event delegation?
  23. What is deep copy vs shallow copy?
  24. Explain the concept of hoisting in functions.
  25. What are arrow function limitations?

Advanced Level

  1. What is garbage collection?
  2. How JavaScript manages memory?
  3. What is JIT compilation?
  4. Difference between call, apply, and bind?
  5. What is a polyfill?
  6. What is SSR (Server-Side Rendering)?
  7. How to improve JavaScript performance?
  8. What are web workers?
  9. What is the observer pattern?
  10. What is the singleton pattern?
  11. What is tail call optimization?
  12. What is tree shaking?
  13. What is lexical scope?
  14. Difference between lexical and dynamic scope?
  15. What is a transpiler?
  16. What is event loop starvation?
  17. What are memory leaks and fixes?
  18. How does the V8 engine work?
  19. What is microtask and macrotask?
  20. What is module bundling?
  21. What is IndexedDB?
  22. What is localStorage vs sessionStorage?
  23. What is a monorepo?
  24. What are micro-frontends?
  25. What is differential loading?

Expert Level

  1. How to optimize rendering in large apps?
  2. Explain event loop phases.
  3. What is speculative execution?
  4. How does JS handle concurrency?
  5. What are WeakMaps and WeakSets?
  6. How to build custom event emitter?
  7. What is memory profiling?
  8. What is Shadow DOM?
  9. What is a service worker?
  10. What is offline-first architecture?
  11. Explain differential serving.
  12. What is module federation?
  13. How does JS handle integer overflow?
  14. What are low-level browser APIs?
  15. Explain WebAssembly integration.
  16. How to implement data virtualization?
  17. Heap vs stack memory difference.
  18. Task queue vs microtask queue.
  19. How modern bundlers optimize JS?
  20. What is dead code elimination?
  21. What is API middleware?
  22. Explain JavaScript engine internals.
  23. What is edge computing relevance to JS?
  24. How browsers ensure security?
  25. How to build a reactive framework core?

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