Question

var document = "temp";

function showDocument()
{
    alert(document); // temp or HTML DOM Document
}

It showed “HTML DOM Document” for me, which should be the case. Is it an object, reserved keyword, read-only object?

If it’s an object, it should be editable. If it’s a reserved keyword, JavaScript should throw an error/exception. If it’s read-only, how can I modify the DOM itself which is accessible through document only?

Answer 1

It’s a read-only property of the global (window) object. Its value is a native object representing the current HTML/XML/whatever document loaded into the window.

To modify the DOM, use DOM manipulation APIs.

edit — to clarify, the “document” property of the window object (or, if you prefer, the global variable called “document”) is itself immutable, and its value cannot be changed by JavaScript. The value, however, is a reference to an object, an object that is mutable in all sorts of ways.