我可以创建一个被隐式转换为数字的javascript对象吗？ [英] Can I create a javascript object that is casted implicitly as number?

问题描述

我想创建一个具有多个公共变量和方法的类，但应用算术运算符时，它的行为类似于数字。例如：

I want to create a class that has several public variables and methods,but behaves as number when arithmetic operators are applied.Example :

 
            a = new hyperNum(4)
            a.func(4)
            a.assign(2.0)
            alert(a + 1.0) `//3.0`

我知道我可以重载Number对象，但是我认为会有一定的开销， 。
当我尝试继承Number时，出现错误：

I know I can just overload the Number object but then I think that there would be a certain overhead for all numbers. When I tried to inherit from Number ,I got an error:

function hyperNum () {}
hyperNum.prototype = new Number();
hyperNum.prototype.z = function(q){this.q = q;}
h = new hyperNum(2);
h+5
/* error:
TypeError: Number.prototype.valueOf is not generic
    at Number.valueOf (native)
    at Number.ADD (native)
    at [object Context]:1:2
    at Interface. (repl:96:19)
    at Interface.emit (events:31:17)
    at Interface._ttyWrite (readline:309:12)
    at Interface.write (readline:147:30)
    at Stream. (repl:79:9)
    at Stream.emit (events:31:17)
    at IOWatcher.callback (net:489:16)

*/

编辑：

 hyperNum.prototype.valueOf = function(){return this.q;}

创建了。

但是仍然最好使用不同的对象或者只是扩展Number对象？

However still is it better to use a different object or just to extend the Number object?

推荐答案

实现 valueOf ，无需扩展 Number 即可：

function Foo(val) {
  this.val = val;
}
Foo.prototype.valueOf = function() {
  return this.val;
};
Foo.prototype.toString = function() {
  return "Foo: " + this.val;
};

display("f = " + f);                      // "f = 42"
display("f + 1 = " + (f + 1));            // "f + 1 = 43"
display("f * 2 = " + (f * 2));            // "f * 2 = 84"
display("f as a string = " + String(f));  // "f as a string = Foo: 42"

实例

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