//getHobbies的返回值类型List的泛型参数是String类 ParameterizedType genericReturnType = (ParameterizedType) getHobbies.getGenericReturnType(); assert genericReturnType.getActualTypeArguments()[0] == String.class; Method setHobbies = User.class.getDeclaredMethod("setHobbies", List.class); //setHobbies...
or even to get the return type of a function. We can use this to build a “FnReturnType” type, that will give us the return type of the function passed in as the generic parameter.
class GenericNumber<T> { zeroValue: T; add: (x: T, y: T) => T; } let myGenericNumber = new GenericNumber<number>(); myGenericNumber.zeroValue = 0; myGenericNumber.add = function (x, y) { return x + y; };12.3 泛型变量对刚接触 TypeScript 泛型的小伙伴来说,看到 T 和 E,...
propertyKey: string | symbol - 方法名 parameterIndex: number - 方法中参数的索引值 function Log(target: Function, key: string, parameterIndex: number) { let functionLogged = key || target.prototype.constructor.name; console.log(`The parameter in position ${parameterIndex} at ${functionLogged} ...
expression, we can use the “infer” keyword to either get the type of the elements of an array, or even to get the return type of a function. We can use this to build a “FnReturnType” type, that will give us the return type of the function passed in as the generic parameter....
泛型(Generic)提供了一种在消费API对象时按需添加约束类型的能力,从而不必固定在某个单一的类型约束上,而是按使用的实际情况时具体约束。 基本用法如下: 函数(function) 语法 functionA<T>{}functionB<T,K>{} 使用 functiongetProperty<T,KextendskeyofT>(obj:T,key:K){returnobj[key];}letx={a:1,b:2,c...
Search Terms conditional type inference enum enumerated narrowing branching generic parameter type guard Suggestion Improve inference / narrowing for a generic type parameter and a related conditional type. I saw another closed-wontfix i...
本文是阅读小册「《深入浅出TypeScript》」的阅读笔记,对TypeScript感兴趣的同学请继续阅读吧。 原始类型 「TypeScript」的原始类型包括:「boolean、number、string、void、undefined、null、symbol、bigint。」 需要注意的是,number是类型,而Number是构造函数。
classGreeter{// 静态属性staticcname:string="Greeter";// 成员属性greeting:string;// 构造函数 - 执行初始化操作constructor(message:string){this.greeting=message;}// 静态方法staticgetClassName(){return"Class name is Greeter";}// 成员方法greet(){return"Hello, "+this.greeting;}}letgreeter=newGreeter...
Type 'string' cannot be used to index type 'T'when indexing a generic function parameter#47357 New issue Bug Report 🔎 Search Terms Type 'string' cannot be used to index type 'T'. 🕗 Version & Regression Information This is the behavior in every version I tried, and I reviewed the...