The global "Window" & "Document" Objects

 Built-in Variables & Functions

Global "Window" Object 

Holds information and functionality related to the active browser window/tab

The document Object (window.document)

Holds information and functionality to the loaded website content 

The Browser Object Model (BOM)

There are no official standards for the Browser Object Model (BOM).

Since modern browsers have implemented (almost) the same methods and properties for JavaScript interactivity, it is often referred to, as methods and properties of the BOM.

The Window Object

The window object is supported by all browsers. It represents the browser's window.

All global JavaScript objects, functions, and variables automatically become members of the window object.

Global variables are properties of the window object.

Global functions are methods of the window object.

Even the document object (of the HTML DOM) is a property of the window object: