It does not wait for the timer will skip this code inside
Performed outside 1 3 undefind 2
He began by saying ah: node is a callback function;
So the node is to have a callback function? These callbacks gave us a good package
So we write
The second is when the parameters are functions, callback functions are slightly
Modular: require, expores only have Node.js
Browser modular solutions: require.js sea.js will be possible
Because many rely on, sometimes the installation package will automatically update the other dependencies. So the original version may not use our original dependence
