Typescript : SyntaxError: Unexpected token 'export'

Question

IN my React project I have need to share models(typescript interfaces in my case) between 3 typescript projects. So I opted for bit.env and imported all my models to https://bit.dev/model/index/~code and its all good.

Then I had a need to verify fields in my model so I added utility functions to https://bit.dev/model/index/~code#util.ts and deployed the same to bit.env

I started facing following error when I tried to use this helper function in my project #2 (place where I keep firebase cloud functions).

/Users/vinoth.gopu/Documents/mine/oss/Cloud/functions/node_modules/@bit/model.index/dist/index.js:1
export * from './admin';
^^^^^^

SyntaxError: Unexpected token 'export'
    at wrapSafe (internal/modules/cjs/loader.js:1101:16)
    at Module._compile (internal/modules/cjs/loader.js:1149:27)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:1205:10)

My code in project #2

export const placeOrder = functions
    .runWith({
        memory:'256MB'
    })
    .region(cloudConfig.firebase.region)
    .firestore
    .document('Orders/{OrderId}')
    .onCreate((snap, context) => {
        const orderDetails = snap.data() as UserOrders;

        try {
            //check if all fields of interface implemented
            if(isOrder(orderDetails)) { // PROBLEM HERE
                 //do something
            }

As pointed out in the code above I can use all interfaces from that model project but helper function throwing error message.

I referred to these articles and links

But none of them seems to work(also I was bit confused which project needs transpilation shared model or Project #2 in my case?). I can understand that this is some problem with node where it cant recognise ES6 module and requires some sort of intermediate transpilation. But I am wondering how all interfaces with similar export statement are working very fine. I would like to understand what am I missing here.

what version of typescript are you using? please give version local to the project if you have one, otherwise global version? — weagle08
– weagle08, Commented May 28, 2020 at 3:16

Robert Mennell · Accepted Answer · 2020-05-27 20:28:59Z

2

NodeJS uses the CommonJS way of loading packages by default. With newer version of NodeJS you do get the Module functionality of JavaScript using either .mjs files or telling the engine the project is a module-based project.

I don't know if FireBase uses the latest Node versions, but this should at least explain why you're seeing that error. JS got support for Export long after NodeJS had already started wrapping things in CommonJS which is why it was such a problem to implement. Legacy support is almost always painful.

You can fix this by changing to CommonJS, or following the steps outlined in the NodeJS ESM page linked.

As for why this is needed for exported functions but not for exported Interfaces, it's because an Interface compiled to JS from TS is... nothing. Literally nothing. JS doesn't have a typing system, and so when TS gets compiled, anything that isn't needed is resolved to be excluded from compilation to the JS target.

edited May 27, 2020 at 20:28

answered May 27, 2020 at 19:25

Robert Mennell

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5 Comments

Robert Mennell Over a year ago

yes, that should be fine. That should tell it to compile to CommonJS and then it should work with NodeJS no problem.

Robert Mennell Over a year ago

firebase.google.com/docs/functions/typescript this might be helpful

Codex Over a year ago

For functions I use exact same format. I tried what has been mentioned above (adding tsconfig and set commonJS) but same outcome. What I am wondering is how come same 'export' style is working for interfaces but not for simple const/function? Thank you Robert

Robert Mennell Over a year ago

interfaces are TS, and when compiled often aren't included because JS has no need for them.

Robert Mennell Over a year ago

updated answer to include why interfaces aren't compiled to JS

Codex · Accepted Answer · 2020-06-01 16:15:48Z

2

It seems answer lies within bit.dev

"bit": {
    "env": {
      "compiler": {
        "bit.envs/compilers/[email protected]": {
          "rawConfig": {
            "tsconfig": {
              "compilerOptions": {
                "target": "ES5",
                "module": "CommonJS"
              }
            }
          }
        }
      }
    },
    "componentsDefaultDirectory": "src/{name}",
    "packageManager": "npm"
  },

Solved my issue by taking care of transpilation.

answered Jun 1, 2020 at 16:15

Codex

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