constobj:Object= {name:'Tom',age:30, };// ⛔️ Error: Property 'country' does// not exist on type 'Object'.ts(2339)obj.country='Chile'; 我们将obj变量键入为Object并尝试访问该对象的country属性。 但是,Object类型上不存在country属性,
If you need to add properties after object creation, one approach is to use type assertions in TypeScript. Here is an example. interface User { id: number; name: string; } // Create initial object const user = { id: 1 } as User; // Add the missing property user.name = "Jane Smi...
AI代码解释 "use strict";var__importStar=(this&&this.__importStar)||function(mod){if(mod&&mod.__esModule)returnmod;varresult={};if(mod!=null)for(varkinmod)if(Object.hasOwnProperty.call(mod,k))result[k]=mod[k];result["default"]=mod;returnresult;};Object.defineProperty(exports,"__es...
Object.prototype.hasOwnProperty()没有这样做;如果你真的对此有强烈的感觉，你可能想要file a suggestion...
interfaceLion{roar():void}interfaceSeal{singKissFromARose():void}asyncfunctionvisitZoo(lionExhibit:Promise<Lion>,sealExhibit:Promise<Seal|undefined>){let[lion,seal]=awaitPromise.all([lionExhibit,sealExhibit]);lion.roar();// uh oh// ~~~// Object is possibly 'undefined'.} 这种...
// 定义一个对象constperson={name:"John",age:30,gender:"male"};// 遍历对象的所有键,并获取对应的值for(constkeyinperson){if(person.hasOwnProperty(key)){constvalue=person[key];console.log(key+": "+value);}}/* 输出: name: John
function logProperty(target: any, key: string) { delete target[key]; const backingField = "_" + key; Object.defineProperty(target, backingField, { writable: true, enumerable: true, configurable: true }); // property getter const getter = function (this: any) { ...
has(element: any){// Object原型有hasOwnProperty方法用于判断对象是否有特定属性returnObject.prototype.hasOwnProperty.call(this.items,element);} 实现向集合中添加元素函数(add) add(element: any){if(!this.has(element)){this.items[element] = element;returntrue;}returnfalse;} ...
val && typeof val === "object" && "x" in val && "y" in val && typeof val.x === "number" && typeof val.y === "number"; } } function f(value: unknown) { if (value instanceof Point) { // Can access both of these - correct! value.x; value.y; // Can't access ...
function extend<T, U>(first: T, second: U): T & U { let result = <T & U>{}; for (let id in first) { (<any>result)[id] = (<any>first)[id]; } for (let id in second) { if (!result.hasOwnProperty(id)) { (<any>result)[id] = (<any>second)[id]; } } return ...