In JavaScript, what data structure is used to store key-value pairs?

In JavaScript, the data structure designed specifically to store key-value pairs is the Object. Objects are fundamental to JavaScript and can hold multiple values as properties, where each property is defined by a unique key. This allows for efficient organization and retrieval of data based on the keys, making it easy to access values when needed.

An Object can be created using curly braces {} and can include various key-value pairs, like so: const myObject = { key1: value1, key2: value2 };. The keys in an Object are strings (or Symbols), and they map to values that can be of any data type, including other Objects, arrays, or primitive data types such as numbers or strings.

In contrast, while Arrays are also key-value structures, they are primarily numeric keyed collections used for ordered lists. Sets store unique values without keys, whereas Queues are more specialized data structures used for managing elements in a first-in-first-out manner. Therefore, the Object is the correct choice when specifically discussing key-value pair storage in JavaScript.