test.js

/**
 * Onion ring model
 */

async function fn1(next) {
    console.log('fn1')
    await next()
    console.log('end fn1')
}

async function fn2(next) {
    console.log('fn2')
    await delay()
    await next()
    console.log('end fn2')
}

function fn3(next) {
    console.log('fn3')
}

function delay() {
    return new Promise((resolve, reject) => {
        setTimeout(() =>{
            resolve()
        }, 2000)
    })
}

function compose (middlewares) {
    return function () {
        return dispatch(0)

        function dispatch(i) {
            let fn = middlewares[i]
            if (!fn) {
                return Promise.resolve()
            }
            return Promise.resolve(fn(function next() {
                return dispatch(i + 1)
            }))
        }
    }
}

const middlewares = [fn1, fn2,fn3]

const finalFn = compose(middlewares)

finalFn()



 


















// /**
//  * 中间件
//  */

// function add (x, y) {
//     return x + y;
// }

// function double (z) {
//     return z * 2
// }

// // const res1 = add(1, 2)
// // const res2 = double(res1)
// // console.log(res2)

// // const res3 = double(add(1, 2))
// // console.log(res3)

// const middlewares = [add, double]
// let len = middlewares.length
// function compose(midds) {
//     return (...args) => {
//         // 初始值
//         console.log('...args', ...args)
//         let res = midds[0](...args)
//         console.log('res', res)
//         for (let i = 1; i < len; i++) {
//             res = midds[i](res)
//         }
//         return res
//     }
// }

// const fn = compose(middlewares)
// const res = fn(1,2)
// console.log(res)




















/**
 * get
 * set
 */

// let yuze = {
//     _name: '语择',
//     get name() {
//         return this._name
//     },
//     set name(value) {
//         console.log('new name is '+ value)
//         this._name = value
//     }
// }

// console.log(yuze.name)
// yuze.name = 'yoa'
// console.log(yuze.name)