串联继承两个具有相同签名的方法

Question

下面的代码只打印事件内容，如何打印 WheatherData.value 数字？我来自java，我习惯这样做。

const Event = (time, place) => {
    var _time = time
    var _place = place

    return {
        getTime() {
            return _time
        },
        getPlace() {
            return _place
        },
        updateTime() {
            _time = new Date(Date.now())
        },
        toString() {
            return 'Time: ' + _time + '\nPlace: ' + _place
        }
    }
}

const WeatherData = (value, time, place) => {
    var _event = Event(time, place)
    var _value = value
    const getValue = () => { return _value }
    const toString = () => { return '\nValue: ' + _value + _event.toString() }
    return Object.assign({ getValue, toString }, _event)
}



const wd = WeatherData(10.1, new Date(Date.now()), 'Chisinau, Moldova')

console.log(wd.toString())

//Time: Sat Sep 18 2021 08:49:10 GMT+0200 (Central European Summer Time)
//Place: Chisinau, Moldova
// no value printed

Answer 1

return Object.assign({ getValue, toString }, _event)

上面一行导致了问题。当您将 _event 对象分配给 { getValue, toString } 对象时，您只是覆盖了 WeatherData 函数的 toString 方法。相反，只需 return { getValue, toString } 来自您的 WeatherData 函数，如下所示；

const WeatherData = (value, time, place) => {
    var _event = Event(time, place);
    var _value = value

    const getValue = () => { return _value }
    const toString = () => { return '\nValue: ' + _value + '\n' + _event.toString() }

    return { getValue, toString }
}

Answer 2

return Object.assign({}, _event, { getValue, setValue, toString })

这对我有用，这是正确的方法吗？我用这种方式覆盖了event的toString方法

串联继承两个具有相同签名的方法

concatenative inheritance two methods with same signature

javascript

inheritance

object

javascript-objects