The difference between the BOM and 1.DOM
DOM: Document Object Model, the [documentation] [as a target] to look at, DOM object is a top-level document
The main study of the operating elements on the page, DOM is the W3C standards
BOM: browser object model, the [browser] as a [target] to look at, is the top-level object BOM window
The main learning is that some of the objects interact with the browser window, BOM browser vendors are defined in their respective browsers, relatively poor compatibility
2.BOM composition
It contains more than BOM DOM DOM
window（document，location，navigation，screen，history）
3.window object is a top-level object browser, it has a dual role
① It is JS browser window to access an interface
② It is a global object, is defined in global scope variables, functions, properties and methods will become window object
Window may be omitted at the time of the call, you are all learned previously dialog window object methods such as alert (), prompt (), etc.
Note: A special property under the window window.name