JavaScript Built-In Objects

A JavaScript variable can be categorized as either a Primitive type or an Object type. The Object data type is versatile and can encompass various object types.

JavaScript Objects

In JavaScript, objects are used to represent complex data structures and provide functionalities that go beyond primitive data types like string, number, and boolean. Objects are defined using curly braces { } and consist of different properties. Each property is a name:value pair, separated by commas.

Built-In Object Types

JavaScript offers a variety of built-in object types, which include:

• Array: A collection of values accessed via numerical indices.
• Map: A collection of key-value pairs, with keys of any data type.
• Set: A collection of unique values.
• WeakMap: Similar to Map, but with weak references to objects.
• WeakSet: Similar to Set, but with weak references to objects.
• Math: Provides mathematical constants and functions such as PI and random().
• Date: Used for managing dates and times.
• RegExp: Facilitates working with regular expressions.
• Error: Represents error conditions during code execution.
• JSON: Includes methods for parsing and stringifying JSON data.
• Promise: Represents the eventual completion (or failure) of an asynchronous operation.
• Int8Array, Int16Array, Int32Array: Arrays for storing fixed-size integer values of different bits.
• Float16Array, Float32Array, Float64Array: Arrays for storing fixed-size floating-point numbers.
• BigInt64Array: Array for storing fixed-size big integer values.

The typeof Operator

The typeof operator in JavaScript is used to determine the type of a variable or an expression. It provides a straightforward way to check the data type being used.

JavaScript Arrays

JavaScript arrays are a specialized form of objects, written with square brackets [ ]. Array items are separated by commas. Here is an example of an array named cars, which holds three car names. Array indexes start at zero, meaning the first item is at position [0], the second at [1], and so on.

let cars = ["Toyota", "Ford", "BMW"];