Top 10 JavaScript Interview Questions Every Developer Should Know
Prepare for your next JavaScript interview with these essential questions covering closures, prototypes, async/await, and more.
Prepare for Your JavaScript Interview
JavaScript interviews can be tricky. Here are the top 10 questions you should be ready to answer.
1. What is the difference between == and ===?
The == operator performs type coercion before comparison, while === checks both value and type without coercion.
2. Explain closures in JavaScript
A closure is a function that has access to variables in its outer (enclosing) scope, even after the outer function has returned.
3. What is the event loop?
The event loop is JavaScript's mechanism for handling asynchronous operations. It continuously checks the call stack and task queue, moving tasks from the queue to the stack when the stack is empty.
4. What is hoisting?
Hoisting is JavaScript's behavior of moving declarations to the top of their scope during compilation. var declarations are hoisted and initialized to undefined, while let and const are hoisted but not initialized.
5. Explain prototypal inheritance
JavaScript uses prototypal inheritance where objects can inherit directly from other objects through the prototype chain.
6. What are Promises?
Promises represent the eventual result of an asynchronous operation. They can be in one of three states: pending, fulfilled, or rejected.
7. What is the difference between let, const, and var?
varis function-scoped and hoistedletis block-scoped and not hoistedconstis block-scoped, not hoisted, and cannot be reassigned
8. What is the this keyword?
this refers to the object that is executing the current function. Its value depends on how the function is called.
9. What are arrow functions?
Arrow functions are a concise syntax for writing functions. They don't have their own this, arguments, or super.
10. What is destructuring?
Destructuring is a syntax for extracting values from arrays or properties from objects into distinct variables.
Practice These Questions
Test your knowledge with our JavaScript Fundamentals quiz or explore our quiz templates for more interview prep.
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