Array-Like Objects

Array‑like objects are objects that have a length property and indexed elements but do not have array methods. Common examples include the arguments object, HTML collections (like NodeList), and strings. They can be converted to real arrays using Array.from() or Array.prototype.slice.call().

Key Points

• They have numeric indices and a length property.
• They do not inherit from Array.prototype, so they lack methods like map, filter.
• You can access elements using bracket notation.

Code Example

// An array-like object
const arrayLike = {
  0: "a",
  1: "b",
  2: "c",
  length: 3,
};

console.log(arrayLike[0]); // "a"
console.log(arrayLike.length); // 3

// But cannot use array methods
// arrayLike.forEach is undefined

// Convert to array
const realArray = Array.from(arrayLike);
console.log(realArray); // ["a", "b", "c"]

// Alternative: slice
const anotherArray = Array.prototype.slice.call(arrayLike);
console.log(anotherArray); // ["a", "b", "c"]