AppConfiguration.ts

import { AppConfigurationClient, ConfigurationSettingId } from "@azure/app-configuration";
import FeatureContext from "../Contracts/FeatureFlags/FeatureContext";
import { FeatureName } from "./FeatureNames";
import { IAppConfiguration } from "../Contracts/FeatureFlags/IAppConfiguration";

export class AppConfiguration implements IAppConfiguration {
  private connectionString: string;
  private environment: string
  private client: AppConfigurationClient;

  constructor(connectionString: string, environment: string) {
    this.connectionString = connectionString;
    this.environment = environment;
    this.client = new AppConfigurationClient(this.connectionString);
  }

  getFeature(featureName: FeatureName): Q.Promise<FeatureContext> {
    const environment = this.environment;
    const featureConfig = this.getFeatureFlagOptions(featureName);
    return (this.client.getConfigurationSetting(featureConfig)
      .then(function (result) {
        if (result && result.value) {
          return JSON.parse(result.value)
        }
      })
      .catch(function (error) {
        if (error && error.statusCode === 404) {
          throw new Error(`Could not find config with key ${featureName} on env: ${environment}`);
        }
        throw error;
      }) as unknown as Q.Promise<FeatureContext>)
  }

  private getFeatureFlagOptions(key: FeatureName): ConfigurationSettingId {
    return {
      key: `.appconfig.featureflag/${key}`,
      label: this.environment,
    }
  }

}

tsconfig.json

{
  "compileOnSave": true,
  "compilerOptions": {
    "baseUrl": "Client",
    "composite": true,
    "declaration": true,
    "emitDecoratorMetadata": true,
    "experimentalDecorators": true,
    "forceConsistentCasingInFileNames": true,
    "inlineSources": true,
    "module": "amd",
    "moduleResolution": "node",
    "noEmitHelpers": true,
    "noImplicitAny": true,
    "noImplicitThis": true,
    "outDir": "Output/Content/Scripts",
    "paths": {
      "*": [
        "*"
      ]
    },
    "removeComments": false,
    "rootDir": "Client",
    "sourceMap": true,
    "strictBindCallApply": true,
    "target": "es5",
    "types": []
  },
  "plugins": [{"name": "typescript-tslint-plugin"}],
  "include": [
    "Client/**/*",
    "Definitions/**/*"
  ]
}

unrealted-file.ts

let timer = setTimeout(() => {
  this._publishVerificationResultNotification(
    result,
    clientValidationNotification,
    timer
  );
  timer = this._pollApplicationStatus(result, clientValidationNotification);
}, validationRetryInterval);

// Here's a completely unrelated file where `setTimeout` returns `NodeJS.Timeout` intead of `number`