Set是一种集合类型,它存储唯一的值。 代码语言:txt 复制 let setOfNumbers: Set<number> = new Set([1, 2, 3, 4]); let setOfStrings: Set<string> = new Set(["a", "b", "c"]); 4. 使用Map Map是一种键值对的集合,其中键和值可以是任意类型。
let strings: string[] = pluck(person, ['name', 'name', 'name']); //["Jarid", "Jarid", "Jarid"] 所谓的小试牛刀,就是结合上面我们说的那几个点,分析下pluck方法的意思 <T, K extends keyof T>约束了这是一个泛型函数 keyof T就是取 T 中的所有的常量 key(这个例子的调用中),即为:"n...
*/type Partial<T>={[PinkeyofT]?:T[P]};/** * From T pick a set of properties K */type Pick<T,KextendskeyofT>={[PinK]:T[P]};/** * Construct a type with a set of properties K of type T */type Record<Kextendsstring,T>={[PinK]:T}; 这里还有两个关于映射类型的例子,如果需...
class Base {get foo() {return 100;}set foo() {// ...}}class Derived extends Base {foo = 10;// ~~~// error!// 'foo' is defined as an accessor in class 'Base',// but is overridden here in 'Derived' as an instance property.}class Base {prop = 10;}class Derived extends Ba...
const [user, setUser] = React.useState<IUser>({} as IUser); 实际上,这里将空对象{}断言为IUser接口就是欺骗了TypeScript的编译器,由于后面的代码可能会依赖这个对象,所以应该在使用前及时初始化 user 的值,否则就会报错。 下面是声明文件中 useState 的定义: ...
String literal types in TypeScript allow us to model functions and APIs that expect a set of specific strings. Copy function setVerticalAlignment(pos: "top" | "middle" | "bottom") { // ... } setVerticalAlignment("middel"); // ~~~ // error: Argument of type '"middel"' is not assign...
typealias NodeSet = Set<Network.Node> typealias FileTable<K> = MutableMap<K, MutableList<File>> 1. 2. 3. 你可以为函数类型提供不同的别名: typealias MyHandler = (Int, String, Any) -> Unit typealias Predicate<T> = (T) -> Boolean ...
String literal types in TypeScript allow us to model functions and APIs that expect a set of specific strings. Copy functionsetVerticalAlignment(color:"top"|"middle"|"bottom"){// ...}setVerticalAlignment("middel");// ~~~// error: Argument of type '"middel"' is not assignable to// parame...
setText(text, start, length); // ... return { getStartPos: () => startPos, getTextPos: () => pos, getToken: () => token, getTokenPos: () => tokenPos, getTokenText: () => text.substring(tokenPos, pos), getTokenValue: () => tokenValue, ...
type Proxy<T> = { get(): T; set(value: T): void; } type Proxify<T> = { [P in keyof T]: Proxy<T[P]>; } function proxify<T>(o: T): Proxify<T> { // ... wrap proxies ... } let proxyProps = proxify(props); 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 注意Read...