Create a JavaScript representation of "Enum".

create-enum.js

/**
 * ✅ Function for creating an `enum` representation in JavaScript.
 *
 * This function will receive a plain object
 * [key: string]: number | string | boolean.
 * You've created the enum with a valid object and it will return you a
 * Proxy. You are not able to extend the proxy anymore.
 *
 * @author 📩 Sajeeb Ahamed <[email protected]>
 *
 */
export const createEnum = (structure) => {
  if (structure === null || typeof structure !== 'object' || Array.isArray(structure)) {
    throw Error(`'${structure}' is not a valid enum structure.`);
  }

  for (const key in structure) {
    if (!['number', 'string', 'boolean'].includes(typeof structure[key])) {
      throw Error(
        `You are only allowed to use 'number', 'string' or 'boolean' types, but you are using '${JSON.stringify(
          structure[key]
        )}'`
      );
    }
  }

  return new Proxy(structure, {
    set(target, prop) {
      if (Reflect.has(target, prop)) {
        throw Error(`Cannot assign to '${prop}' because it is a read-only property.`);
      } else {
        throw Error(`Property '${prop}' does not exist on the enum structure.`);
      }
    },
    get(target, prop) {
      return Reflect.get(target, prop);
    },
  });
};

//------------------------------------------ Create an Enum --------------------------------------------------------

/**
 * 🎉 Use the createEnum function. Here the Status is a non-extendable enum Proxy.
 * 🔖 You are not able to change any property of add a new property.
 */
const Status = createEnum({
  PENDING: 'pending',
  ACCEPTED: 'accepted',
  REJECTED: 'rejected',
});

// ❌ Invalid assignment
Status.PENDING = 'loading'; //Error: Cannot assign to 'PENDING' because it is a read-only property.
Status.NEW_VALUE = 'new-value'; //Error: Property 'NEW_VALUE' does not exist on the enum structure.

const user = {
  id: '3423',
  name: 'John Doe',
  email: '[email protected]',
  status: Status.PENDING,
};

// ✅ The condition is true
if (user.status === Status.PENDING) {
  console.log('Pending user');
}