如何在 Firebase 云函数 Typescript 中定义 const

Question

The error that I am getting: Unhandled error ReferenceError: COLLECTION_A is not defined. When I upload code is no complaints about the code. I do have a need to use the same constant in multiple files. I tried to use namespace but it is not allowed...

How do I need to define constants that will be accessible in every file?

I have multiple files in src foldes:
index.ts
foo.ts
boo.ts
cnst.ts

Inside index.ts:

import * as admin from 'firebase-admin'
admin.initializeApp()

export * from './foo'
export * from './boo'

Inside cnst.ts:

const COLLECTION_A = "pathA"
const COLLECTION_B = "pathB"

Inside foo.ts I am trying to access const from cnst.ts

...
admin
        .firestore()
        .collection(COLLECTION_A)
...

Answer 1

I figured out! But I don't like it!

Is there any better approach?? Or more correct in terms of good practice. I don't like this approach very much as a variable can be changed, But it should be const!!

inside cnst.ts I defined a new class:

export class Const {
    static COLLECTION_A = "pathA"
    static COLLECTION_B = "pathB"
}

And inside foo.ts I import it like this:

import { Const } from './cnst'
...    
...
    .collection(Const.COLLECTION_A)
...

---

I figured out also approach with constants:

inside cnst.ts

export const COLLECTION_A = "pathA"
export const COLLECTION_B = "pathB"

And inside foo.ts I import it like this:

import { COLLECTION_A } from './cnst'
...    
...
    .collection(COLLECTION_A)
...

I like second approach more since I am using constants. Is there any other way that would be suitable for my case?

Answer 2

Another approach is to use the outFile flag. According to Typescript documentation this flag allows user to:

Concatenate and emit output to single file. The order of concatenation is determined by the list of files passed to the compiler on the command line along with triple-slash references and imports.

This strategy will scale with your program much better than manually referencing specific files everywhere.

Check documentation for more details.