BOM（Browser Object Model）
// IE browser
// FireFox browser
window.sidebar.addPanel(title, url, "");
Although there is no unified standard, the js code of common functions of various browsers is similar, and there are default standards for common functions.
DOM（Document Object Model）
DOM is the document object model. DOM is the W3C standard. The most fundamental object of DOM is document (window.document). This object is actually an attribute of the window object. The uniqueness of this object is that this is the only one that belongs to both BOM and DOM object.
The DOM is related to the document, and the document here refers to the web page, that is, the html document. DOM has nothing to do with the browser. What he cares about is the content of the web page itself. Since it has nothing to do with the browser, the standard is set.