Array-like Objects

An array-like object is any object that has:

• A length property.
• Indexed elements (i.e., properties with numerical keys).

Array-like objects do not have the standard array methods like push(), forEach(), or map().

Common examples of array-like objects include:

• Arguments object in functions.
• NodeList objects returned by methods like document.querySelectorAll.
• HTMLCollection objects

Example

function example() {
  console.log(arguments); // Arguments object, array-like but not a true array

  let argsArray = Array.from(arguments);
  console.log(argsArray); // Now it's a true array
}

example(1, 2, 3);
// Output:
// Arguments(3) [1, 2, 3, callee: ƒ, Symbol(Symbol.iterator): ƒ]
// [1, 2, 3]