模块一作业

爱被打了一巴掌 2022-12-21 09:28 185阅读 0赞

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80NTM0NTEwNQ_size_16_color_FFFFFF_t_70_pic_center]  
异步编程：

EventLoop：js中每个代理都是由事件循环驱动的，事件循环负责收集等待的任务，安排等待的任务执行。先执行微任务然后宏任务，然后开始事件循环，**总之EventLoop负责监听调用栈和消息队列**。

消息队列：当JS有异步任务时，首先异步任务会进入WebApi等待任务执行，异步任务开始执行时会（回调函数执行）进入消息队列，（事件循环监听到）然后放入调用栈执行任务。

宏任务：同步代码和setTimeout等属于宏任务，宏任务会在微任务结束后执行。  
微任务：Promise和queueMicroTask等属于微任务，调用栈执行宏任务前会检查微任务是否有任务，如果有就先执行微任务的，当微任务执行过程中再放入微任务，这个时候这个刚刚放入的微任务不会等到下一轮事件循环执行，而是马上执行，微任务执行完后会开启渲染线程，渲染完成后执行宏任务。

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80NTM0NTEwNQ_size_16_color_FFFFFF_t_70_pic_center 1]  
答案：

var a 
    var b
    var c
     Promise.resolve('hello ')
     .then(v =>{ 
          a = v
         return 'lagou '
     }).then(v=>{ 
          b = v
         return 'love u'
     }).then(v =>{ 
         c = v
        console.log(a+b+c);
    })

![在这里插入图片描述][20201117224054711.png_pic_center]  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80NTM0NTEwNQ_size_16_color_FFFFFF_t_70_pic_center 2]  
答案：

let f = fp.flowRight(fp.prop('in_stock'),fp.last)
    console.log(f(cars));

![在这里插入图片描述][20201117224902396.png_pic_center]  
答案：

let f = fp.flowRight(fp.prop('name'),fp.first)
    console.log(f(cars));

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80NTM0NTEwNQ_size_16_color_FFFFFF_t_70_pic_center 3]  
答案：

let f = fp.flowRight(_average,fp.map(function(car){ 
                return car.dollar_value
            }))
    console.log(f(cars));

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80NTM0NTEwNQ_size_16_color_FFFFFF_t_70_pic_center 4]  
答案：

let arr = ["hello world","ni hao"]
    let _underscore = fp.replace(/\W+/g,"_")
     function sanitizeNames(){ 
        return fp.flowRight(fp.map(_underscore))
    }
    console.log(sanitizeNames()(arr)); //[ 'hello_world', 'ni_hao' ]

![在这里插入图片描述][20201118171222255.png_pic_center]

class Container { 
        static of(v) { 
            return new Container(v)
        }
        constructor(v){ 
            this._v = v
        }
        map(fn){ 
            return Container.of(fn(this._v))
        }
    }
    
    class Maybe { 
        static of(v){ 
            return new Maybe(v)
        }
        constructor(v){ 
            this._v = v
        }
        isNothing(){ 
            return this._v === null ||
            this._v === undefined
        }
        map(fn){ 
            return this.isNothing() ? this :
            Maybe.of(fn(this._v))
        }
    }

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80NTM0NTEwNQ_size_16_color_FFFFFF_t_70_pic_center 5]答案：

let maybe = Maybe.of([5,6,1])
    let exl = (v)=>{ 
     return fp.map(fp.add(1),v)
    }
    console.log(maybe.map(exl));
    // Maybe { _v: [ 5, 6, 1 ] }
    // Maybe { _v: [ 6, 7, 2 ] }

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80NTM0NTEwNQ_size_16_color_FFFFFF_t_70_pic_center 6]

答案：

// console.log(
        Container.of(['c','s','a']).map( (v)=>{ 
            return fp.first(v)
        })
        // );
        // Container { _v: 'c' }

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80NTM0NTEwNQ_size_16_color_FFFFFF_t_70_pic_center 7]

答案：

let safeProp = fp.curry(function(x,o){ 
        return Maybe.of(o[x])
    })
    let user = { id:1,name:'Albert'}
    let exl3 = ()=>{ 
        let m = safeProp('name',user)
         return fp.first(m._v)
    }
    console.log(exl3());//A

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80NTM0NTEwNQ_size_16_color_FFFFFF_t_70_pic_center 8]  
TODO 实现low 问问  
答案：

let ex4 = (n)=>{ 
        let d2o = false
       d2o =  Maybe.of(n)._v === null || Maybe.of(n)._v === undefined
       
       d2o || console.log(parseInt(n));
    }

![在这里插入图片描述][20201118172153899.png_pic_center]

class Mypromise{ 
        constructor(excecutor){ 
            try { 
                excecutor(this.res, this.rej)
            } catch (e) { 
                this.rej(e)
            }    
        }
    
        status = PENDING
        value = undefined
        reason = undefined
        successCall = []
        failCall = []
        res = (v)=>{ 
            if(this.status !== PENDING) return
            this.value = v
            this.status = 'fulfilled'
        
            while(this.successCall.length) this.successCall.shift()()
            
    
        }
        rej = (v)=>{ 
            if(this.status !== PENDING) return
            this.reason = v
            this.status = 'rejected'
            
            while(this.failCall.length) this.failCall.shift()()
            
        }
        static res(v){ 
            if(v instanceof Mypromise) return v
            return new Mypromise((res,rej)=>{ res(v)})
        }
        static all(arr){ 
    
           let  result = []
           let index = 0
          
    
          return  new Promise((res,rej)=>{ 
                function add(i,item){ 
                    result[i] = item
                    index++
                    if(index === arr.length){ 
                        res(result)
            
                        }
                   
                }
                for(let i =0 ;i < arr.length;i++){ 
                    let current = arr[i]
                    if(current instanceof Mypromise){ 
                        current.then(value =>{ add(i,value)},reason =>rej(reason))
                    }else{ 
                        add(i,arr[i])
                    }
                }
              
            })
           
           
        }
        catch(failCall){ 
            return this.then(undefined,failCall)
        }
        finally(calBack){ 
            return this.then(res=>{ 
                return Mypromise.res(calBack()).then(()=> value)
            },rej=>{ 
                return Mypromise.res(calBack()).then(()=> { throw reason})
            })
        }
        then = (successCall,failCall)=>{ 
            
            // 没有就把v赋值给successCall
            successCall = successCall ? successCall : v => v
            failCall = failCall ? failCall : reason => {  throw reason}
            let p2 = new Mypromise((res,rej)=>{ 
                if(this.status === 'fulfilled'){ 
                    
                    
                  setTimeout(()=>{ 
                    try { 
                        let x =   successCall(this.value)
                        resolvePromise(p2,x,res,rej)
                    } catch (e) { 
                        rej(e)
                    }
                   
                  },0)
              
                  }else if(this.status === 'rejected'){ 
                       
                       
                       setTimeout(()=>{ 
                        try { 
                            let x =    failCall(this.reason)
                            resolvePromise(p2,x,res,rej)
                        } catch (e) { 
                            rej(e)
                        }
                       
                      },0)
                  }else{ 
                         this.successCall.push(()=> setTimeout(()=>{ 
                            try { 
                                let x =   successCall(this.value)
                                resolvePromise(p2,x,res,rej)
                            } catch (e) { 
                                rej(e)
                            }
                           
                          },0))
                         this.failCall.push(()=>
                              setTimeout(()=>{ 
                            try { 
                                let x =    failCall(this.reason)
                                resolvePromise(p2,x,res,rej)
                            } catch (e) { 
                                rej(e)
                            }
                           
                          },0))
                  } 
            })
            
           return p2
        }  
    }
    
    function resolvePromise(p2,x,res,rej){ 
        if(p2 === x){ 
            return rej(new TypeError('Chaining cycle detected for promise #<Promise>'))
        }
        if(x instanceof Mypromise){ 
            x.then(res,rej)
         
        }else{ 
            res(x)
        }
    }

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