Cannot evaluate property value inline

Question

I cannot evaluate a property inline in a nested dictionary. If I evaluate the property into a separate local variable, it works. Why is that?

This throws an error

const appConfig = {
  config.networks!.testnet?.chainId! : {
    "token1": "mytoken"
  }
};

This works

const chainId = config.networks!.testnet?.chainId!;
const appConfig = {
   chainId : {
    "token1": "mytoken"
  }
};

Not sure, so how should I reference the chain id with proper syntax? — siamii, Aug 30 '23 at 19:58
I see, so I guess I need to add it later, cannot add it during initialization — siamii, Aug 30 '23 at 20:01
A nomenclature hint: In TypeScript/JavaScript, we call them "objects", not "dictionaries". The answers to the linked question are quite clear: Use the bracket syntax to add the property (e.g., `{ [chainId] : { token1: "mytoken" } }`). — Heretic Monkey, Aug 30 '23 at 20:01

Dimava · Answer 1 · 2023-08-30T20:06:09.517

1

Because you forgot the brackets
... in BOTH cases

const appConfig = {
  [config.networks!.testnet?.chainId!] : {
    "token1": "mytoken"
  }
};

const chainId = config.networks!.testnet?.chainId!;
const appConfig = {
   [chainId] : {
    "token1": "mytoken"
  }
};

Typescript is not Python, chainId key means string "chainId" key

Also you can only have string (and number, and symbol) keys (everything else (including numbers) is cast to string)
If you need to use objects as keys, use new Map<KeyType, ValueType>(pairs: [KeyType, ValueType][])

edited Aug 30 '23 at 20:06

answered Aug 30 '23 at 20:01

Dimava

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thanks, so why is the second one not throwing error then? the one with the local variable – siamii Aug 30 '23 at 20:07
@siamii because it's `const appConfig = { "chainId" : { "token1": "mytoken" } };` (`chainId` interpreted as literal string key) . It would still work if you delete the line with variable – Dimava Aug 30 '23 at 20:08

Cannot evaluate property value inline

1 Answers1