TypeScript的开放式函数参数 [英] open-ended function arguments with TypeScript

问题描述

IMO是> TypeScript 语言的主要关注点之一，它支持现有的vanilla JavaScript代码。这是我乍一看的印象。看看以下完全有效的JavaScript函数：

IMO, one of the main concerns of the TypeScript language is to support the existing vanilla JavaScript code. This is the impression I had at first glance. Take a look at the following JavaScript function which is perfectly valid:

注意：我并不是说我喜欢这种方法。我只是说这是一个
有效的JavaScript代码。

Note: I am not saying that I like this approach. I am just saying this is a valid JavaScript code.

function sum(numbers) { 

    var agregatedNumber = 0; 
    for(var i = 0; i < arguments.length; i++) { 
        agregatedNumber += arguments[i];
    }

    return agregatedNumber;
}

因此，我们使用任意数量的参数来使用此函数：

So, we consume this function with any number of arguments:

console.log(sum(1, 5, 10, 15, 20));

然而，当我尝试使用 TypeScript Playground ，它会产生编译时错误。

However, when I try this out with TypeScript Playground, it gives compile time errors.

我假设这是一个错误。我们假设我们没有兼容性问题。那么，有没有办法用开放式参数编写这种类型的函数？比如C＃中的 params 功能？

I am assuming that this is a bug. Let's assume that we don't have the compatibility issues. Then, is there any way to write this type of functions with open-ended arguments? Such as params feature in C#?

推荐答案

TypeScript的做法这是将省略号运算符（ ... ）放在参数名称之前。以上内容将被写为，

The TypeScript way of doing this is to place the ellipsis operator (...) before the name of the argument. The above would be written as,

function sum(...numbers: number[]) {
    var aggregateNumber = 0;
    for (var i = 0; i < numbers.length; i++)
        aggregateNumber += numbers[i];
    return aggregateNumber;
}

这将使用

console.log(sum(1, 5, 10, 15, 20));

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