JavaScript

Question

我真的想让 Date.now() 作为属性可用，而不是函数调用或方法。换句话说，我想要 clock.now.go 到 return 一个 unix 时间戳。我无法让它工作。 returned 时间戳与原始调用停滞不前。下面是显示控制台结果的代码。是否可以通过调用属性来触发新的时间戳，或者是否需要函数调用，即“()”？

//Revealing Module Pattern (Public & Private) 
var clock = (function() {

    // object to expose as public via return
    var pub = {};

    //constructor function
    function Now() {
        this.getNow = function() {
            return ( Date.now() );
        };
        this.go = this.getNow();
    }

    //private
    var now = new Now();
    //public
    pub.test1 = now;
    pub.test1.go;  //clock.test1.go returns 1461888755076
    pub.test1.getNow();  //clock.test1.getNow() returns 1461888767477 (GOOD)
    pub.test2 = now.getNow();  //clock.test2 returns 1461888755076 (STALE)
    pub.test3 = now.go;  //clock.test3 returns 1461888755076 (STALE)
    //Return just the public parts
    return pub;
}());

Answer 1

如果您希望它显示为属性，但实际上是一个实时函数调用，那么您可以使用 Javacript getter.

//Revealing Module Pattern (Public & Private) 
var clock = (function() {

    // object to expose as public via return
    var pub = {};

    Object.defineProperty(pub, "now", {
        get: function () { 
            return Date.now();
        }
    });
    return pub;
}());

console.log(clock.now);   // returns live time

或者，可以浓缩为：

//Revealing Module Pattern (Public & Private) 
var clock = (function() {

    // object to expose as public via return
    var pub = { 
        get now() { 
            return Date.now();
        }
     };
     return pub;
}());

console.log(clock.now);   // returns live time

或者，即使只是这样（没有封闭模块模式）：

var clock = { 
    get now() { 
        return Date.now();
    }
 };

console.log(clock.now);   // returns live time

Answer 2

你可以用这样的 getter

var obj = {
           _time : "",
           get time () {
             this._time = new Date();
             return this._time;
           },
           set time(val) {
             this._time = val;
           }
};

document.write("<pre>" + obj.time + "</pre>");

JavaScript - 属性生命周期和构造方法触发

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JavaScript - 属性 生命周期和构造方法触发

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JavaScript - 属性生命周期和构造方法触发