是否可以仅针对打字稿上的特定类型扩展Array.prototype？ [英] Is it possible to extend Array.prototype only for a specific type on typescript?

问题描述

我具有以下原型扩展，因为我一直在使用很多 reduce ：

I have the following prototype extension because I've been using a lot of reduce:

declare interface Array<T> {
    sum(): T;
}

Array.prototype.sum = function() {
    return this.reduce((acc, now) => acc = acc + now, 0);
};

是否可以强制仅以数字键入此扩展名？

推荐答案

在我写问题时，我终于找到了解决方法：

As I wrote the question, I ended up finding out how to do it:

declare interface Array<T> {
    sum(this: Array<number>): number;
}

Object.defineProperty(Array.prototype, 'sum', {
    value: function(this: Array<number>): number {
        return this.reduce((acc, now) => acc = acc + now, 0);
    },
});

还应注意，扩展基本原型通常不是一个好主意-如果基础更改了标准以实现新功能，您自己的代码库中可能会发生冲突。对于我特定代码库中的特定示例，我觉得很好，因为 sum 是一个描述性很强的方法名称，并且在多种语言中非常常见，因此将来的标准（可能）是具有兼容的实现。

It should also be noted that extending basic prototypes is usually not a good idea - in the event the base standard is changed to implement new functionality, there might be a conflict in your own code base. For this particular example on my particular codebase I feel it is fine, since sum is a fairly descriptive method name and very common along multiple languages, so a future standard will (probably) have a compatible implementation.

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