Question

好的，所以我试图想出一个很好的例子，所以我创建了一个关于贵金属的构造函数。构造函数采用金属和重量类型。我有两种方法。一种方法确定贵金属（金或银）是否真实，另一种方法根据现货价格计算价值。（我知道现货价格是错误的，这只是一个例子）。

假设一位顾客带来了一块80％银的银片。因为它的80％银我想把它应用到我的metalValue方法。我该怎么做。

这是代码。（JSFiddle为您提供了便利http://jsfiddle.net/bwj3fv12/）。这将有助于我更好地理解构造函数。

HTML

<div id="testDiv">test Div</div>
<div id="testDiv2">test Div2</div> <br /><br />

的JavaScript

var PreciousMetals = function(metal, weight){
    this.metal = metal;
    this.weight = weight;  //weight in ounces

    this.authentic = function(colorTest){
        var metalPurity;
        var zero = "";
        if (this.metal == "silver"){
            switch(colorTest){
                case "brightred":
                    metalPurity = 1;
                    break;
                case "darkred":
                    metalPurity = 0.925;
                    break;
                case "brown":
                    metalPurity = 0.80;
                    break;
                case "green":
                    metalPurity = 0.50;
                    break;
                default:
                    metalPurity = 0;
            }


        }else if(this.metal == "gold"){
            switch(colorTest){
               case "green":
                   metalPurity = "base metal or gold plated";
                   break;
               case "milk colored":
                   metalPurity = "gold plated sterling silver";
                   break;
               case "no color":
                   metalPurity = "real gold";
                   break;
               default:
                   metalPurity = "Could be a fake, try different test";
            }
        }
        return metalPurity;
    }

    this.metalValue = function(metal){
        var sum = 0;
        var spotPrice;
        if (this.metal == "gold"){
           spotPrice = 1000;
        }else if(this.metal == "silver"){
           spotPrice = 15;
        }
        sum = spotPrice * this.weight;
        return sum;        
    }
}


var customerCindy = new PreciousMetals("silver", 2);

document.getElementById('testDiv').innerHTML = customerCindy.authentic("brown");


document.getElementById('testDiv2').innerHTML = customerCindy.metalValue();  //The result I would like would be 24 of course.

现在我意识到我可以这样做：

document.getElementById('testDiv2').innerHTML = customerCindy.metalValue() * customerCindy.authentic("brown");

然而，这里的目标是从真实方法中获取信息并使用它来帮助我计算metalValue方法中的金属值。

Answer 1

如果您想在构造函数中将这两个方法的逻辑分开，则可以包含第三个执行将两个结果相乘的任务的方法。

var PreciousMetals = function(metal, weight){
    this.metal = metal;
    this.weight = weight;  //weight in ounces

    this.authentic = function(colorTest){
        var metalPurity;
        var zero = "";
        if (this.metal == "silver"){
            switch(colorTest){
                case "brightred":
                    metalPurity = 1;
                    break;
                case "darkred":
                    metalPurity = 0.925;
                    break;
                case "brown":
                    metalPurity = 0.80;
                    break;
                case "green":
                    metalPurity = 0.50;
                    break;
                default:
                    metalPurity = 0;
            }


        }else if(this.metal == "gold"){
           switch(colorTest){
                case "green":
                    metalPurity = "base metal or gold plated";
                    break;
                case "milk colored":
                    metalPurity = "gold plated sterling silver";
                    break;
                case "no color":
                    metalPurity = "real gold";
                    break;
                default:
                    metalPurity = "Could be a fake, try different test";
            }
        }
        return metalPurity;
    }

    this.metalValue = function(){
        var sum = 0;
        var spotPrice;
        if (this.metal == "gold"){
           spotPrice = 1000;
        }else if(this.metal == "silver"){
           spotPrice = 15;
        }
        sum = spotPrice * this.weight;
        return sum;        
    }

    this.netValue = function(colorTest){
        return this.authentic(colorTest) * this.metalValue();    
    }
}

这是一个有效的JSFiddle - https://jsfiddle.net/bwj3fv12/

Answer 2

如果您想更新metalValue以包含纯度检查的结果，您可以更新

this.metalValue = function(colorTest){
    // ...
    sum = spotPrice * this.weight * this.authentic(colorTest);
    return sum;        
}

并用

调用它

customerCindy.metalValue('brown');

由于这只是一个例子，因此没有理由担心它，但可能现实世界中的纯度与金属和重量一样多，并且不会出现这种情况。 t实际上是这种方法的瞬态值。但那既不在这里，也不在那里。

如何从自定义方法获取信息并将其应用于我的构造函数javascript中的另一个方法？

2 个答案: