use of const enum may produce unexpected results

[bennypowers]

Shavua tov.

The flags dict is defined as a typescript const enum. This can lead to difficulties:

https://www.typescriptlang.org/play?target=9&jsx=0#code/JYWwDg9gTgLgBAbzgMwDYEMDmBnOBfFKCEOAcgAEALAUwCMBjdVAenumtIG4AobtgO2zxkcALxwA8rQBW1ejAB0yIiACi-GFGDVsACimz5C6hq07d3OFbjNmccjGwBaagA8wcmC6hEoALjgAd0p0GGoAN2ooS2s0LGxuAEpEnj4IQQhUagVUCExdZBTeAWxM7Nz8uJwFAGEACQBBAHFEoA

Input:

import { flags } from '@hebcal/core';

const f = Object.fromEntries(Object.entries(
    // @ts-expect-error: whatever
    flags
));

console.log(f);

console.log(flags.CHAG)

Output:

const f = Object.fromEntries(Object.entries(
// @ts-expect-error: whatever
flags));
console.log(f);
console.log(0 /* flags.CHAG */);
export {};

The correct flag for CHAG is 1. Code relying on flags.CHAG and thus-compiled will fail. I worked around this by copying the flags table into my code. A better solution would be to export the table as an object

export const flags = {
  // ...
} as const;

An even better solution would be to vend predicates instead of bitmasks.

Besoros tovos

[mjradwin]

Thanks for the bug report! We're sorry about TypeScript errors. Can you try 4.5.1 and let us know if this fixes the problem for you?

[bennypowers]

https://github.com/hebcal/hebcal-es6/commit/dd5b87f00f249494067000faecfab36c6ed2b6ef seems to fix it

if you adopt ts sources, let me suggest using export const flags = {/*..*/} as const instead, which is more flexible