type Level='coder'|'leader'|'boss'functiongetWork(level:Level){if(level==='coder'){console.log('打代码、摸鱼')}elseif(level==='leader'){console.log('造轮子、架构')}elseif(level==='boss'){console.log('喝茶、谈生意')}}getWork('coder')getWork('user')// 类型“"user"”的参数不...
const type = typeMap.get(ctx.routerName) const target = plainToClass(type, ctx.query) const errors = await validate(target) if (!errors.length) return next() ctx.body = { success: false, message: errors.map(error => ({ field: error.property, prompt: error.constraints, })), } } ...
consttmp1:object={name:'linbudu'};consttmp2:object=()=>{};consttmp3:object=[]; Object 表示拥有toString、hasOwnProperty方法的的类型,所以所有的原始类型、非原始类型都可以赋值给Object(严格模式下null和undefined不可以) 代码语言:javascript 复制 letobject:Object;object=1;//正确object='tiantian';//...
Object.getOwnPropertyNames()遍历自身的非Symbol属性,不考虑是否可枚举,getOwnPropertyNames中的Own表示遍历自身属性,PropertyNames表示只遍历普通属性,不遍历Symbol。 Object.getOwnPropertySymbols()只遍历自身的Symbol,不考虑是否可枚举,更强调own和symbol,方法名getOwnPropertySymbols中的Own表示只遍历自身属性,PropertySymbols表...
Object.defineProperty(C.prototype,"foo",__decorate([log],C.prototype,"foo",Object.getOwnPropertyDescriptor(C.prototype,"foo"))); 这就是属性装饰者不返回的原因。 既然我们知道属性装饰器将要装饰的类的原型以及被装饰为属性的属性的名称并且不返回,那么让我们实现logProperty装饰器。
function myPropertyDecorator(target: any, propertyKey: string) { const privateKey = `_${propertyKey}`; Object.defineProperty(target, propertyKey, { get: function () { return this[privateKey]; }, set: function (value) { this[privateKey] = value.toUpperCase(); ...
getOwnMetadataKeys(target); let result = Reflect.getOwnMetadataKeys(target, propertyKey); 如果不传入属性名称,那么查询的是 person 对象自己的元数据。 // 源码 function getMetadata(metadataKey, target, propertyKey) { if (!IsObject(target)) throw new TypeError(); if (!IsUndefined(propertyKey))...
Whenever decorator functions are used, they now have access to a newmetadataproperty on their context object. Themetadataproperty just holds a simple object. Since JavaScript lets us add properties arbitrarily, it can be used as a dictionary that is updated by each decorator. Alternatively, since...
Developers who want to use property-style syntax or any ES5 or proposed ES6 TypeScript features should set this switch. Extra Benefits JavaScript is here to stay and it’s more popular than ever, so those who move to JavaScript from the land of compiled languages now have TypeScript to ...
You can also define object types as classes, which, unlike interfaces, can contain executable code. This example defines a class called CustomerShort with one property and one method: XML class CustomerShort { FullName: string; UpdateStatus( status: string ): string { ...manipulate status......