2019年底

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// 简易版emit/on function Pubsub(){      //存放事件和对应的处理方法     this .handles = {};  }  Pubsub.prototype={      //传入事件类型type和事件处理handle      on:   function (type, handle) {          if (!  this .handles[type]){              this .handles[type] = [];          }          this .handles[type].push(handle);      },      emit:   function () {          //通过传入参数获取事件类型         var type = Array.prototype.shift.call(arguments);         console.log(type,   'type' );          if (!  this .handles[type]){              return false ;          }  for (  var i = 0; i <   this .handles[type].length; i++) {              var handle =   this .handles[type][i];              //执行事件             console.log(handle,   'handle' , arguments);             handle.apply(  this , arguments);          }      },      off:   function (type, handle) {          handles =   this .handles[type];          if (handles){              if (!handle){                  handles.length = 0;  //清空数组             }  else {  for (  var i = 0; i < handles.length; i++) {                      var _handle = handles[i];                      if (_handle === handle){                          handles.splice(i,1);                      }                  }              }          }      }  }    var p1 =   new Pubsub();  p1.on(  'mm' ,   function (name) {      console.log(  'mm: ' + name);  });  p1.emit(  'mm' ,  '哈哈哈哈' );     // 洋葱圈模型 // 实现方式一 function compose (middleware) {    return async   function () {       let args = arguments       await dispatch(0)       function async dispatch (i) {          const fn = middleware[i]          if (!fn)   return null          await fn(  function next () {             dispatch(i + 1)          }, ...args)       }    } } // 实现方式二 function compose(middlewares=[fn1,fn2,fn3]) {     function dispatch(i)     {         let fn=middlewares[i]         if (!fn){             return Promise.resolve()         }         else         {             return new Promise((resolve)=>{                 resolve(fn(  function next () {                     return dispatch(i + 1)                 }));             });         }     }     return dispatch(0); }

　　

 

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本文作者：Paxster
本文链接：https://www.cnblogs.com/paxster/p/12088040.html
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