如何从TypeScript中的对象数组创建类型？
给定一个countries这样的数组：
const countries = [
{ name: "Australia", code: "AU" },
{ name: "Japan", code: "JP" },
{ name: "Norway", code: "NO" },
{ name: "Russian Federation", code: "RU" }
];
生成以下类型的最简单方法是什么？
type CountryCodes = "" | "AU" | "JP" | "NO" | "RU";
注意：有一个额外的空字符串。
回答
虽然从 JS 的角度来看这个函数是没有用的。它能够将代码统一为一种类型。
function createCountries<T extends string>(
contries: { name: string; code: T }[],
): { name: string; code: T }[] {
return contries;
}
const countries = createCountries([
{ name: "Australia", code: "AU" },
{ name: "Japan", code: "JP" },
{ name: "Norway", code: "NO" },
{ name: "Russian Federation", code: "RU" }
]);
type CountryCodes = "" | (typeof countries)[number]["code"]; // "" | "AU" | "JP" | "NO" | "RU";
// Example - How to use the type
function getCountryByCode(code: CountryCode): Country | undefined {
return countries.find(country => country.code == code);
}
类型countries：
{
name: string;
code: "AU" | "JP" | "NO" | "RU";
}[]
没有进一步的信息，这是你能做的最好的......
type Countries = { name: string; code: string }[];
const countriesAbc = [
{ name: "Australia", code: "AU" },
{ name: "Japan", code: "JP" },
{ name: "Norway", code: "NO" },
{ name: "Russian Federation", code: "RU" }
] as const;
const countries: Countries = [...countriesAbc];
type CountryCodes = "" | (typeof countriesAbc)[number]["code"]; // "" | "AU" | "JP" | "NO" | "RU";