There are special built-in symbols that are used by JavaScript for service purposes. Such symbols are called well-known symbols.
An example of such a symbol is
Symbol.iterator
, which
contains a function that iterates
over arrays. Let's check its
presence in some array:
let arr = [1, 2, 3];
let func = arr[Symbol.iterator];
console.log(func);
Make a Map
collection. Check
if it has the Symbol.iterator
key.
Make a Set
collection. Check
if it has the Symbol.iterator
key.