[英]Typescript: Type 'string' is not assignable to type '"numeric" | "2-digit"' in Date::toLocaleDateString()
I have recently been alerted to an "error" by Visual Studio Code in the following snippet:我最近在以下代码段中收到 Visual Studio Code 的“错误”警告:
someDateObject.toLocaleDateString('de-DE', Travel.dateOptions));
someDateObject.toLocaleDateString('de-DE', Travel.dateOptions));
Where Travel.dateOptions is defined as such: Travel.dateOptions 的定义如下:
public static dateOptions = { year: 'numeric', month: '2-digit', day: '2-digit' };
This has been working fine for the better part of the last 2 years, but upon opening the class inside VSC recently, it displayed following error for Travel.dateOptions
:在过去 2 年的大部分时间里,这一直运行良好,但最近在 VSC 中打开 class 后,它显示Travel.dateOptions
的以下错误:
Argument of type '{ year: string; month: string; day: string; }' is not assignable to parameter of
type 'DateTimeFormatOptions'.
Types of property 'year' are incompatible.
Type 'string' is not assignable to type '"numeric" | "2-digit"'. ts(2345)
I am dead confused as to why.我对为什么感到困惑。 Is this possibly a bug with VSC?这可能是VSC的错误吗? The code seems to work fine (and has worked fine the entire time) once compiled - and according to the documentation for Date::toLocaleDateString() what I'm doing here seems perfectly valid.代码在编译后似乎运行良好(并且一直运行良好) - 根据 Date::toLocaleDateString() 的文档,我在这里所做的似乎完全有效。
Any ideas?有任何想法吗?
When you initialize a class property with a literal such as public foo = { bar: 'a' }
, its type becomes { bar: string }
, even if you declare it as readonly
.当您使用诸如public foo = { bar: 'a' }
类的文字初始化 class 属性时,其类型变为{ bar: string }
,即使您将其声明为readonly
。 TypeScript on purpose doesn't make the type too strict ( { bar: 'a' }
). TypeScript 故意不会使类型过于严格( { bar: 'a' }
)。
Method toLocaleDateString
accepts an object whose key year
must be of type 'numeric'
or '2-digit'
, but yours is of type string
.方法toLocaleDateString
接受一个 object ,其关键year
必须是'numeric'
或'2-digit'
类型,但你的类型是string
。
To make the type of the initialized object more specific, use as const
:要使初始化的 object 的类型更具体,请使用as const
:
public static dateOptions = { year: 'numeric', month: '2-digit', day: '2-digit' } as const;
I've just hit the same problem, rather than redeclare the const as const (which feels like a code smell) I forced the variable type:我刚刚遇到了同样的问题,而不是将 const 重新声明为 const (感觉像代码味道),我强制变量类型:
formatDT(sourceDate: Date) {
const options: Intl.DateTimeFormatOptions = { month: "long", day: 'numeric', year: 'numeric', hour: '2-digit', minute: "2-digit" };
return new Intl.DateTimeFormat("en-GB", options).format(new Date(sourceDate));
}
Following your code example you must explicitly declare the DateTimeFormatOptions
data type for dateOptions
按照您的代码示例,您必须为dateOptions
显式声明DateTimeFormatOptions
数据类型
const dateOptions: Intl.DateTimeFormatOptions = {
year: 'numeric',
month: '2-digit',
day: '2-digit'
};
export const Travel = { dateOptions };
const someDateObject = new Date();
console.log(someDateObject.toLocaleDateString('de-DE', Travel.dateOptions));
Include "Intl.DateTimeFormatOptions" for the declaration.在声明中包含“Intl.DateTimeFormatOptions”。
const options:Intl.DateTimeFormatOptions = { year: 'numeric', month: '2-digit', day: 'numeric', hour: '2-digit', minute: '2-digit', hour12: false };常量选项:Intl.DateTimeFormatOptions = { 年:'数字',月:'2-digit',日:'数字',小时:'2-digit',分钟:'2-digit',hour12:假 };
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