javascript事件监听器,用于更改对象变量

Question

我有一个具有多个属性的对象变量.

MyVar = {"prop1" : 0, "prop2": 0....};

如何编写侦听任何属性更改的事件侦听器.

谢谢你的建议.

Answer 1

使用ES5,您可以设置:

var MyVar = {
  _prop1: 0,
  get prop1() { return this._prop1; },
  set prop1(value) { this._prop1 = value; /*Listener code can go here*/ }
};

Answer 2

如果要在对象变量更改时触发事件,可以为该obj设置一个小的Observer模式.

var MyVar = {
    prop1: "Foo",
    prop2: "Bar",
    events: {},

    setProp1: function(prop1) {
        this.prop1 = prop1;
        this.notify('prop1', this.prop1);
    },

    setProp2: function(prop2) {
        this.prop2 = prop2;
        this.notify('prop2', this.prop1);
    },

    addEvent: function(name) {
        if (typeof this.events[name] === "undefined") {
            this.events[name] = [];
        }
    },

    register: function(event, subscriber) {
        if (typeof subscriber === "object" && typeof subscriber.notify === 'function') {
            this.addEvent(event);
            this.events[event].push(subscriber);
        }
    },

    notify: function(event, data) {
        var events = this.events[event];
        for (var e in events) {
            events[e].notify(data);
        }
    }
};

var Prop1 = {
    notify: function() {
        alert('prop1 changed');
    }
};

var Prop2 = {
    notify: function() {
        alert('prop2 changed');
    }
};

$(document).ready(function(){
    MyVar.register('prop1',Prop1);
    MyVar.register('prop2',Prop2);

    MyVar.setProp1('New Var');
    MyVar.setProp2('New Var');
});

用法而不是直接设置对象属性,您使用setter方法,然后将一个notify事件触发到正在观看它的其他对象.

JS FIDDLE