Add TypeScript support

Issue To Be Solved

Add support for TypeScript, so that autocomplete and other developer tooling works.

(Optional): Suggest A Solution

Solution 1: Rewrite in TypeScript

Pretty self explanatory. Would probably take weeks because TypeScript usually messes you up at edge cases. This would automatically generate type definitions when building to JavaScript.

Solution 2: Add TypeScript declaration file

Create .d.ts file. This would have to be maintained “separately” if the code base stays in plain JavaScript. Separately means here that you might forget to update the .d.ts file and functions don’t conform to it.

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Comparison

Solution 1 (rewrite) is certainly more work than solution 2 (type declarations). TypeScript is widely used right now and many developers would consider it easier to contribute to the codebase after solution 1, if it was fully written in TypeScript - (which may or may not be objectively true).

(Optional): Context

Its not blocking anything, but it makes development a little harder because you always have to check out the docs and (depending on the strictness of your config) TypeScript constantly yells at you for missing types.

[janhesters]

I made a PR with the typings I did for my personal project here. So far it has types for config and onceSealed. Commits / feeback welcome!

[hotrungnhan]

@justinbarry why dont your guy support typescript by default , or using typescript in the future ?