(4)http 模块
回调 将后续函数作为参数放在起始函数中作为参数。
function learn(something) {
console.log(something);}
function we(callback,something) {
something += ' is cool';
callback(something);}
we(learn,'node.js');
we(function (something) {
console.log(something);},"jade");
同步／异步
I／O
