plot({ x: 10, y: 25 }); // Okay. plot({ x: 8, y: 13, name: 'foo' }); // Extra fields Okay. Need enable `suppressExcessPropertyError` 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 细细品味,当真没有一点违和感。理想中的 JavaScript 类型系统就
interfacePoint{x:number;y:number;}interfaceFrozenPoint{readonly x:number;readonly y:number;}functionfreezePoint(p:Point):FrozenPoint{returnObject.freeze(p);}constorigin=freezePoint({x:0,y:0});// Error! Cannot assign to 'x' because it// is a constant or a read-only property.origin.x=4...
console.log(`Get: ${key} => ${currVal}`); return currVal; }; // property setter const setter = function (this: any, newVal: any) { console.log(`Set: ${key} => ${newVal}`); this[backingField] = newVal; }; // Create new property with getter and setter Object.defineProperty(...
AI代码解释 import"reflect-metadata";constresponse:ParameterDecorator=(target:Object,propertyKey:string|symbol,parameterIndex:number)=>{Reflect.defineMetadata("response",parameterIndex,target,propertyKey);};constget:(path:string)=>MethodDecorator=(path)=>{return(target:Object,propertyKey:string|symbol,desc...
{// Proxy - 代理(拦截目标对象的属性操作和函数操作)lettarget = {name:'webabcd',age:40,gethello() {returnthis.name+this.age; } }lethandler = {get:function(target:any, propertyKey:string, receiver:any) {// receiver 就是 Proxy 实例本身console.log("get: "+ propertyKey);returntarget[prop...
instanceof类型保护如果你已经阅读了typeof类型保护并且对JavaScript里的instanceof操作符熟悉的话,你可能已经猜到了这节要讲的内容。instanceof类型保护是通过构造函数来细化类型的一种方式。比如,我们借鉴一下之前字符串填充的例子:interface Padder { getPaddingString(): string } class SpaceRepeatingPadder implements...
functiongetUrls(url: string | URL, names: string[]){if(typeofurl==="string") {url=newURL(url); }returnnames.map(name => {url.searchParams.set("name", name)// ~~~// error!// Property 'searchParams' does not exist on type 'string | URL'.returnurl.toString(); }); } Here,...
}for(let idinsecond) {if(!result.hasOwnProperty(id)) { (<any>result)[id] = (<any>second)[id]; } }returnresult; }/** * 联合类型*/interface Fish{ swim(); layEggs(); } interface Bird{ fly(); layEggs(); }functiongetSmallPet():Fish |Bird{//...} let...
get tasks() { return this._tasks; } set tasks(value: string[]) { this._tasks = value; } } const dev = new Developer(); // ⛔️ Error: Property '_language' is private // and only accessible within class 'Developer'.ts(2341) ...
(); }; // 替换属性,先删除原先的属性,再重新定义属性 if (delete target[propertyKey]) { Object.defineProperty(target, propertyKey, { get: getter, set: setter, enumerable: true, configurable: true, }); } } class Person { @upperCase name!: string; } let p: Person = new Person(); p...