英文:
Expected 2 arguments but got 1 - but I want to pass just one
问题
我创建了一个具有以下签名的函数：
const createSomething = (
someRange: number[],
{ option }: { option?: boolean }
) =>...
有时我只传递someRange参数给函数，有时传递额外的对象参数。然而，我收到一个错误，函数期望两个参数。如何将第二个参数声明为可选的？
英文:
I created a function with this signature:
const createSomething = (
someRange: number[],
{ option }: { option?: boolean }
) =>...
Sometimes I pass to the function just the someRange argument, and sometime the additional object argument. However I receive an error that the function expects two arguments. How can I declare the second argument to be optional?
答案1
得分: 4
const createSomething = (
someRange: number[],
{ option }: { option?: boolean } = {}
) => {}
当你将鼠标悬停在 createSomething 上时，它显示的签名是前者？？？
无论如何，是的，你可以使用默认值来表示它是可选的。
在回顾中，为什么它无效现在显然很明显。如果第二个参数是 undefined，那么你无法解构它。
<details>
<summary>英文:</summary>
It's quite odd that you can't do:
```ts
const createSomething = (
someRange: number[],
{ option }?: { option?: boolean } // INVALID
) => {}
so you have to do:
const createSomething = (
someRange: number[],
{ option }: { option?: boolean } = {}
) => {}
but then when you hover over createSomething, it shows the signature as the former???
Anyways, yeah, you can use a default value to show that it's optional.
In hindsight, it's quite obvious why it's invalid. If the second parameter is undefined, then you can't destructure it.
答案2
得分: 1
给你的选项对象一个默认值{}，你也可以给option属性一个默认值：
const createSomething = (
someRange: number[],
{ option = false }: { option?: boolean } = {}
) => {
console.log(option);
};
createSomething([1]); // 编译并显示false
英文:
Give your options object a default value {}, you can also give the option property a default value as well:
const createSomething = (
someRange: number[],
{ option = false }: { option?: boolean } = {}
) => {
console.log(option);
};
createSomething([1]); // Compiles and displays false
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