在 TypeScript 中,Map 也可以被视为一种对象类型,并且可以使用 for…in 循环来遍历其键。 下面是一个使用 for…in 循环遍历 Map 键的示例代码: constmap=newMap<number,string>();map.set(1,"one");map.set(2,"two");map.set(3,"three");for(constkeyinmap){if(map.hasOwnProperty(key)){console...
functionLog(target:Function,key:string,parameterIndex:number){letfunctionLogged=key||target.prototype.constructor.name;console.log(`The parameter in position${parameterIndex}at${functionLogged}has been decorated`);}classGreeter{greeting:string;constructor(@Log phrase:string){this.greeting=phrase;}}// c...
枚举类型的值可以是字符串。枚举可以反向映射,也就是可以key<=>value。 常量枚举 代码语言:javascript 代码运行次数:0 运行 AI代码解释 constenumDirection{Up='Up',Down='Down',Left='Left',Right='Right'}consta=Direction.Up; 好处是编译成JavaScript后,会直接去除Direction的声明,来提升性能。 联合枚举类型 ...
function Log(target: Function, key: string, parameterIndex: number) { let functionLogged = key || target.prototype.constructor.name; console.log(`The parameter in position ${parameterIndex} at ${functionLogged} has been decorated`); } class Greeter { greeting: string; constructor(@Log phrase:...
If you’re writing a set of functions that all work on string | number | boolean, you can write a type alias to avoid repeating yourself over and over again. Copy type BasicPrimitive = number | string | boolean; TypeScript has always used a set of rules and guesses for when to reuse...
declare const nationalBirds: Map<string, Bird>; function makeNationalBirdCall(country: string) { const bird = nationalBirds.get(country); // bird has a declared type of Bird | undefined if (bird) { bird.sing(); // bird has type Bird inside the if statement } else { // bird has ty...
//Property 'name' has no initializer and is not definitely assigned in the constructor. } class GoodGreeter { name: string; constructor() { this.name = "hello"; } } 请注意,该字段需要在构造函数本身中进行初始化。 TypeScript 不会分析你从构造函数调用的方法来检测初始化,因为派生类可能会覆盖这...
If your package has typings specified using the types or typings key in its package.json, the npm registry will display that the package has available bindings like so: If you still can't find the typings, just look for any ".d.ts" files in the package and manually include them with ...
🗺️Road map Features that are planned: Promise support. Something likeassertOrReject<Type>(object)will eitherresolve(object)orreject(error). Optimize the generated conditions. Things likefalse || "key" === "key"can be simplified. Might be more interesting to publish a different library that...
ExecuteRun Build Task(⇧⌘B(Windows, LinuxCtrl+Shift+B)) from the globalTerminalmenu. If you created atsconfig.jsonfile in the earlier section, this should present the following picker: Select thetsc: buildentry. This will produce aHelloWorld.jsandHelloWorld.js.mapfile in the workspace. ...