深入浅析Nodejs中的“洋葱模型”

const Koa = require('koa');

const app = new Koa();

/**

 * 中间件 1

 */

app.use(async (ctx, next) => {

    console.log('first');

    await next();

    console.log('first end');

});

/**

 * 异步中间件

 */

app.use(async (ctx, next) => {

    console.log('async');

    await next();

    await new Promise(

        (resolve) =>

            setTimeout(

                () => {

                    console.log(`wait 1000 ms end`);

                    resolve()

                },

            1000

        )

    );

    console.log('async end');

});