Js異步並行與串行

1、概述

用普通函數和promise分別實現了兩個版本的Js異步並行與串行。最關鍵的地方在與執行函數的實現，下面貼出代碼來記錄一把。

2、異步並行

class Executor {

    constructor() {
        this.tasks = [];
        this.tasksPromise = [];
    }
    register(name, fn) {
        this.tasks.push(fn);
    }
    execute(...args) {
        let finalCall =args.pop(),
            index=0,
            done=()=>{
                index++;
                if(index==this.tasks.length){
                    finalCall(); 
                }
            };
        this.tasks.forEach(fn=>fn(...args,done));
    }

    registerPromise(name, fn) {
        this.tasksPromise.push(fn);

    }
    executePromise(...args) {
      this.tasksPromise = this.tasksPromise.map(fn=>fn(...args));
        return Promise.all(this.tasksPromise);
    }
}

let excutor = new Executor();
excutor.register('TaskA',function(data,cb){
    setTimeout(() => {
       console.log(data,'task A....'); 
      cb();
    }, 1000);
})
excutor.register('TaskB',function(data,cb){
    setTimeout(() => {
       console.log(data,'task B....');
       cb();
    }, 1000);
})
excutor.execute('普通異步並行......',function(){
    console.log('普通異步並行 end----');
})
excutor.registerPromise('PromiseA', function (data) {
    return new Promise((resolve, reject) => {
        setTimeout(() => {
            console.log(data,'Promise A....');
            resolve(data);
        }, 3000);
    });

})
excutor.registerPromise('PromiseB', function (data) {

    return new Promise((resolve, reject) => {
        setTimeout(() => {
            console.log(data,'Promise B....');
            resolve(data);
        }, 3000);
    });
})
excutor.executePromise('Promise異步並行......').then(function() {
    console.log('Promise end------');
})
複製代碼

3、異步串行

class Executor {

    constructor() {
        this.tasks = [];
        this.tasksPromise = [];
    }
    register(name, fn) {
        this.tasks.push(fn);

    }
    execute(...args) {
        let index = 0;
        let finalCallback = args.pop();

        let next = (data) => {
            if (index == this.tasks.length) return finalCallback(data);
            let task = this.tasks[index];

            if (index == 0) {
                task(...args, next);
            } else {
                task(data, next);
            }
            index++;
        }
        next(...args);
    }

    registerPromise(name, fn) {
        this.tasksPromise.push(fn);

    }
    executePromise(...args) { 
        let index = 0;
        let p;
        let next = (data) => {
            p = this.tasksPromise[index++](data);
            if (index == this.tasksPromise.length) {
                return p;
            } else {
                return p.then(d => next(d));
            }
          }
        return next(...args)
        }
    }

let excutor = new Executor();
excutor.register('TaskA',function(data,cb){
    setTimeout(() => {
       console.log(data); 
       cb('task A....');
    }, 1000);
})
excutor.register('TaskB',function(data,cb){
    setTimeout(() => {
       console.log(data);
       cb('task B....');
    }, 1000);
})
excutor.execute('普通異步串行......',function(data){
    console.log(data);
    console.log('普通異步串行end---');
})
excutor.registerPromise('PromiseA', function (data) {
    return new Promise((resolve, reject) => {
        setTimeout(() => {
            console.log(data);
            resolve('Promise A....');
        }, 3000);
    });

})
excutor.registerPromise('PromiseB', function (data) {
   return new Promise((resolve, reject) => {
        setTimeout(() => {
            console.log(data);
            resolve('Promise B....');
        }, 3000);
    });
})
excutor.executePromise('Promise異步串行......').then(function (data) {
    console.log(data);
    console.log('Promise異步串行 end------');
})
複製代碼