javascript - 如何在 typescript 中导入/使用 Reflect

Question

我正在尝试使用 this SO answer 中的代码.它使用反射。这是一个副本:

export function CustomComponent(annotation: any) {
  return function (target: Function) {
    var parentTarget = Object.getPrototypeOf(target.prototype).constructor;
    var parentAnnotations = Reflect.getMetadata('annotations', parentTarget);

    var parentAnnotation = parentAnnotations[0];
    Object.keys(parentAnnotation).forEach(key => {
      if (isPresent(parentAnnotation[key])) {
        annotation[key] = parentAnnotation[key];
      }
    });
    var metadata = new ComponentMetadata(annotation);

    Reflect.defineMetadata('annotations', [ metadata ], target);
  }
}

首先，我得到了这两个错误:

Property 'getMetadata' does not exist on type 'typeof Reflect'.
Property 'defineMetadata' does not exist on type 'typeof Reflect'.

然后我运行了npm install reflect-metadata，但我不知道如何使用它。

import { Reflect } from reflect-metadata;

Module '".../node_modules/reflect-metadata/index"' has no exported
member 'Reflect'.

或者

import { Reflect } from 'reflect-metadata/Reflect';

Cannot find name 'Record'. 
Type '{}' is not assignable to type 'V'.
File '.../node_modules/reflect-metadata/Reflect.ts' is not a module.

或者

import "reflect-metadata"

rollup: Treating 'fs' as external dependency 
bundle update failed: Error transforming .../node_modules/typescript/lib/typescript.js
with 'commonjs' plugin: The keyword 'package' is reserved (57066:28) in
.../node_modules/typescript/lib/typescript.js 

或者

var reflect = require("reflect-metadata");

Cannot find name 'require'.

或者

declare var require: any;
var reflect = require("reflect-metadata");
var Reflect = reflect.Reflect;

    rollup: Treating 'fs' as external dependency 
bundle update failed: Error transforming .../node_modules/typescript/lib/typescript.js
with 'commonjs' plugin: The keyword 'package' is reserved (57066:28) in
.../node_modules/typescript/lib/typescript.js

当然，我只是遗漏了一些愚蠢的东西，甚至是错字。我可以做什么来使用此代码？

Answer 1

您必须将类型声明与 (js) 库一起导入

npm install reflect-metadata -D

在您的 .ts 文件中:

 import "reflect-metadata";