JavaScript Trivia Questions

Sample JavaScript Quiz Questions

A mix of easy, medium and hard — questions run from warm-up to expert, so there's a real challenge at every level. Think you know the answers? Play to find out.

1. 1.In a web browser, this built-in function displays a popup dialog box with a message and an OK button.

   Difficulty: Easy
   • alert()
   • prompt()
   • confirm()
   • console.log()

2. 2.This object represents the eventual completion or failure of an asynchronous operation and its resulting value.

   Difficulty: Medium
   • Promise
   • Observable
   • Callback
   • Future

3. 3.This technique prevents creating multiple instances of an object by caching and returning the existing instance.

   Difficulty: Hard
   • Singleton pattern
   • Factory pattern
   • Prototype pattern
   • Builder pattern

4. 4.This keyword declares a variable that cannot be reassigned after its initial value is set.

   Difficulty: Easy
   • var
   • const
   • let
   • static

5. 5.This keyword pauses async function execution until a Promise is settled and returns its result.

   Difficulty: Medium
   • yield
   • async
   • await
   • defer

6. 6.This V8 optimization technique compiles frequently executed bytecode directly to machine code for faster execution.

   Difficulty: Hard
   • Interpretation
   • Baseline compilation
   • JIT compilation
   • AOT compilation

7. 7.This operator checks both value and type equality, returning true only when both match exactly.

   Difficulty: Easy
   • ==
   • !=
   • ===
   • =>

8. 8.This method creates a shallow copy of a portion of a string as a new string.

   Difficulty: Medium
   • splice()
   • slice()
   • split()
   • substr()

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