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← Introduction to JavaScript
○What is JavaScript?○Your First JavaScript Code○Data Types●Type Checking
○Declaring Variables○let and const in Practice○Operators○Type Conversion
○Conditionals○Switch Statement○For Loops○While Loop○Break and Continue
○Defining Functions○Arrow Functions○Scope○Closures○Project - Calculator○Function Expressions
○Arrays○Array Mutation Methods○Array Search and Slice○Array Iteration Methods○Multidimensional Arrays○Destructuring○Array Reverse and Sort○Array Fill○Array Find and Includes○Array Flat and FlatMap○Array Reduce, Some, and Every
○Objects○Object Methods and Destructuring○JSON○Math and Date○Date Basics
○02 Template Literals○String Methods○Regular Expressions
○Higher-Order Functions○Callbacks○map, filter, and reduce○Recursion○Project - Data Transform Pipeline
○OOP Introduction○Classes○Inheritance○Encapsulation
○Asynchronous JavaScript○Promises and Async Await○Async API Simulation

Type Checking

Beginners quickly notice that typeof [] is not as useful as they expect. This lesson teaches the practical pair: typeof for primitives and Array.isArray() for arrays.

Example

javascript
console.log(typeof "hello");
console.log(Array.isArray([1, 2, 3]));

Your Task

  1. Create messageType from typeof 'hello' and isList from Array.isArray([1, 2, 3]).
  2. Display string | true in #output.
Hint 1
1 / 2
HINT 1

Use typeof for primitive values like strings.

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