Browser kernel module composition

Browser kernel module ：
The main thread
1、js Engine modules ： be responsible for js Program compilation and operation
2、html、CSS Document parsing module ： Responsible for parsing page text
3、DOM/CSS modular ： be responsible for DOM/CSS Related processing in memory
4、 Layout and rendering module ： Responsible for the layout and rendering of the page （ Objects in memory ）
Sub thread
Timer module ： Responsible for the management of timers
Event response module ： Responsible for the management of events
Web request module ： be responsible for Ajax request
js Is the thread
js It's single-threaded （ The callback function is also executed in the main thread ）
H5 The implementation scheme of multithreading is proposed ：Web Worker ----->Worker
Can only be updated in the main thread DOM