发布订阅模式——JavaScript实现

前言

发布订阅模式有个亲戚，叫观察者模式，他们比较相似。发布订阅模式是多对多的联系，观察者模式是一对多的联系。
例如，多个老师给多个同学布置作业，这样的场景就需要发布订阅模式来实现了。

模式实现

1 原型方法

var Teacher = function (type) {
    this.type = type;
    this.pubObjects = [];
}
Teacher.prototype = {
    pubObject: function (student) {
        if (this.pubObjects.indexOf(student) < 0 && student instanceof Student) {
            this.pubObjects.push(student);
        }
    },
    assignWork: function () {
        let length = this.pubObjects.length;
        for (var i = 0; i < length; i++) {
            console.log(this.pubObjects[i].name, " need to do ", this.type);
        }
    }
}
var Student = function (name) {
    this.name = name;
    this.objects = [];
}
Student.prototype = {
    subObject: function (teacher) {
        if (this.objects.indexOf(teacher) < 0 && teacher instanceof Teacher) {
            this.objects.push(teacher);
        } else {
            console.log("had sub it.");
        }
    },
    doWork: function () {
        let length = this.objects.length;
        for (var i = 0; i < length; i++) {
            console.log(this.name, " do ", this.objects[i].type);
        }
    }
}

2 使用示例

var yw = new Teacher('yw');
var sx = new Teacher('sx');

var xm = new Student('xm');
var xh = new Student('xh');

yw.pubObject(xm);
yw.pubObject(xh);

xm.subObject(yw);
xm.subObject(sx);

yw.assignWork();

xm.doWork();

3 输出结果

xmlxm  need to do  yw
xh  need to do  yw
xm  do  yw
xm  do  sx