错误的一个常见原因是我们忘记等待promise。 asyncfunctionexample(){// 👇️ forgot to use awaitconstresult =Promise.resolve('hello world');// ⛔️ Error: Type 'Promise<string>' is// not assignable to type 'string'.ts(2322)constgreeting:string= result;returngreeting; } 函数中的结果变量...
For local development, running tests still requires a full type-check from TypeScript by default, with compilation from esbuild. This is partially necessary to run certain tests. For example, we store a "baseline" or "snapshot" of TypeScript’s declaration files. Whenever our public API chang...
import{ValidateClass,AssertType}from'typescript-is';@ValidateClass()classA{asyncmethod(@AssertType({async:true})value:number){// You can safely use value as a numberreturnvalue;}methodPromise(@AssertType({async:true})value:number):Promise<number>{// You can safely use value as a numberretur...
When checking if a union is assignable to some target type, we have to check if every member of the union is assignable to the target type, and that can be very slow. In TypeScript 5.3, we peek at the original intersection form that we were able to tuck away. When we compare the ...
例如,在将Promise传递给另一个函数之前通常会忘记.then()或await。TypeScript的错误消息现在会明确的告知用户应该考虑使用await关键字。 // ~~~ // Argument of type 'Promise' is not assignable to parameter of type 'User'. // ... // Did you forget...
Argumentoftype'string'is not assignable to parameteroftype'number'.(2345) 我们可以在函数中使用任何类型,而不仅仅是基本类型。例如,假设我们有一个看起来像这样的 User 类型: 代码语言:javascript 代码运行次数:0 运行 AI代码解释 type User={firstName:string;lastName:string;}; ...
比如说,我们的ts文件当中定义一个Promise对象,而这是ES6当中才出现的对象,而对于IE很多都是不支持的,我们看一下打包之后这个Promise对象变成了什么。 8、TS的面向对象 在对于TypeScript的面向对象这里,在JS当中也是有用到的,以及对于其他的编程语言如Java、python、c#等当中也是面向对象,这里后面关于面向对象的代码...
(): Promise<void> {await deleteAsync(["dist/**/*"]);return;}// 编译 ts 文件为 js 文件function buildTypescript(): NodeJS.ReadWriteStream {return src("./src/**/*.ts").pipe(ts({noImplicitAny: false,removeComments: false,esModuleInterop:true,declaration: true,target: "es2017",module...
{this.name=name;}}// -- Babel compiled output -- //"use strict";function_classCallCheck(...
async/await:async关键字用于定义一个异步函数,await关键字用于等待一个 Promise 完成。这使得异步代码看起来更像同步代码,提高了可读性。 异步数据库查询:在getDataFromDatabaseAsync函数中,我们使用 Promise 来封装数据库查询,然后在路由处理函数中使用await来等待查询结果。