AI代码解释 constx:[string,number]=['hello',0]// 上述元组可以看做为:interfaceTupleextendsArray<string|number>{0:string;1:number;length:2;} object。表示非原始类型。比如枚举、数组、元组都是 object 类型。 枚举类型 声明枚举类型时,如果没有显式的赋值,那么枚举值从 0 递增。如果显式赋值,那么后面的...
在联合类型数组上循环时，typescript编译器引发奇怪的错误在我看来，当你输入newIns[i][j]时，在这一...
typeIsArray<T> = Textendsany[] ?true:false;functionfoo<Uextendsobject>(x:IsArray<U>) {letfirst:true= x;// Errorletsecond:false= x;// Error, but previously wasn't} Previously, when TypeScript checked the initializer forsecond, it needed to determine whetherIsArray<U>was assignable to ...
遍历执行 camelizeif(Array.isArray(obj)){returnobj.map(item=>camelize(item));// 如果是对象}elseif(isPlainObjectX(obj)){constnewObj=Object.create(null);Object.keys(obj).forEach(key=>{// 将 key 改为驼峰,对 value 递归
而在 jsscript 中,自然也是沿用了一样的设定,唯一的不同是采用了 TypeScript 的 Tagged Union 而非 C 中的 union,并且采用了更加适合前端的命名规则。 export type JSSaftHostValue = JSNumberValue | JSBoolValue | JSStringValue | JSUndefinedValue | JSNullValue export type JSHostValue = JSSaftHost...
A union type describes a value that can be one of several types. This flexibility can be helpful when a value isn't under your control (for example, values from a library, an API, or user input.)The any type can also accept different types, so why would you want to use a union ...
比如,GraphQL 的类型系统支持代数数据类型(Algebraic data type),可以用 union 定义 A 或 B 的类型关系。这在 Rust和 TypeScript 中有不错的支持,在 Java 或 Go 中还没有直接的支持。然而即便是 TypeScript,很多类型声明也得在 GraphQL 和 TypeScript 中分别定义一份。
A suggestion to create a runtime array of union members was deemed out of scope because it would not leave the type system fully erasable (and because it wouldn't be runtime complete, though that wasn't desired). This suggestion is basic...
var foo: string | any: When any is used in a union type, the resulting type is still any. So, while the string portion of this type annotation may look useful, it in fact offers no additional typechecking over simply using any. Depending on the intention, acceptable alternatives could be...
如果我像[...colorArray]那样包装colorArray,错误就会消失,但它不能解决问题,因为类型保持为String[]。有没有办法解决这个问题,或者有没有其他有吸引力的工作? 如果需要将对象键转换为union类型,只需使用keyof typeof YourConstObject,如下所示: const color = { ...