Characters -> Tokens -> Nodes -> DOM
Request page -> GET html -> page head(build DOM, render) -> search result(build DOM, render)
Characters -> Tokens -> Nodes -> CSSOM
hi tag is faster evaluation than div p tag as dom tree.
JavaScript is parser blocking
Async is a utility module which provides straight-forward, powerful functions for working with asynchronous JavaScript. Although originally designed for use with Node.js and installable via npm install –save async, it can also be used directly in the browser.
