choice-setting.js

export default class ChoiceSetting {
  static storageKey = undefined;
  static label = undefined;
  static defaultValue = undefined;

  static set defaultValue(value) {
    if (failsValidation(value))
      throw new Error();
    this.defaultValue = value;
  }

  static getValueAsync = async () => {
    if (!(this.storageKey && this.label && this.defaultValue))
      throw new Error();
    return SecureStore.getItemAsync(this.storageKey).catch(() => this.defaultValue);
  };

  static setValueAsync = async (value) => {
    if (failsValidation(value))
      throw new Error();
    return SecureStore.setItemAsync(this.storageKey, value);
  };
}

index-complete.js

export default class SettingsStore {
  /**
   *
   * @param {string} userId UUID of currently signed in user
   */
  constructor(userId) {
    this.useBiometricFace = new BooleanSetting(
      "useBiometricFace",
      userId,
      BooleanSetting.States.OFF
    );
    this.useBiometricFinger = new BooleanSetting(
      "useBiometricFinger",
      userId,
      BooleanSetting.States.OFF
    );
    this.useSound = new BooleanSetting(
      "useSound",
      userId,
      BooleanSetting.States.ON
    );
  }

  static appLanguage = class extends ChoiceSetting {
    static label = "appLanguage";
    static CHOICES = Object.freeze({
      en: "en_US",
      fr: "fr_FR",
    });
  };

  static appTheme = class extends ChoiceSetting {
    static label = "appTheme";
    static CHOICES = Object.freeze({
      DEFAULT: "default", // light
      DARK: "dark",
      SYSTEM: "system",
    });
  };
}

index.js

import ChoiceSetting from './choice-setting'
export default class SettingsStore {
  /**
   *
   * @param {string} userId UUID of currently signed in user
   */
  constructor(userId) {
    //... some setup
  }

  static appLanguage = class extends ChoiceSetting {
    static label = "appLanguage";
    static CHOICES = Object.freeze({
      en: "en_US",
      fr: "fr_FR",
    });
  };

  static appTheme = class extends ChoiceSetting {
    static label = "appTheme";
    static CHOICES = Object.freeze({
      DEFAULT: "default", // light
      DARK: "dark",
      SYSTEM: "system",
    });
  };
}