回退：异步中间件模式

倒退 简单的异步中间件模式。 安装 npm install throwback --save 用法 组成异步（返回承诺）功能。 const { compose } = require ( "throwback" ) ; const fn = compose ( [ async function ( ctx , next ) { console . log ( 1 ) ; try { await next ( ) ; } catch ( err ) { console . log ( "throwback" , err ) ; } console . log ( 4 ) ; } , async function ( ctx , next ) { console . log ( 2 ) ; return next ( ) ; } ] ) ; // Callback runs at the end of the stack, before // the middleware bubbles b