JS Built-ins
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ArrayArray.isArrayadvanced

Array.isArray() — distinguish array-like objects

📖 Usage Example
Array.isArray(Array.from('abc'))  // → true  (converted to real array)
Array.isArray({0:'a', length:1})  // → false (array-like, not array)

Use Array.isArray() to distinguish real arrays from array-like objects such as NodeList or arguments.

Array.isArray() — arrays vs array-like objects

An array-like object has a numeric length property (e.g. { length: 2 }, arguments, NodeList) but is not a real array. Array.isArray returns false for them.

Challenge: Implement getType that classifies a value as:

  • 'array' — a real array
  • 'array-like' — a non-array object with a numeric length property
  • 'other' — anything else
getType([1, 2])       // → 'array'
getType({ length: 2}) // → 'array-like'
getType('hello')      // → 'other'
💡 Hints (2)
  • • Check `Array.isArray` first — even a subclass array should return `"array"`.
  • • For "array-like": the value must be an object (not null) with a numeric `length` property.