Composing promises in typescript

compose.ts

// Here's the original article for function composition and piping: https://blog.logrocket.com/how-to-create-compose-function-typescript/

interface Context {
  user: string;
  content: string;
}

// And this is how to implement the same method using Promises:
const compose = <T>(fn1: (a: T) => Promise<T>, ...fns: Array<(a: T) => Promise<T>>) =>
  fns.reduce((prevFn, nextFn) => async (value) => await prevFn(value).then(nextFn), fn1);


const addUser = async (ctx: Context): Promise<Context> => {
  return {
    ...ctx,
    user: 'user123',
  };
}

const addContent = async (ctx: Context): Promise<Context> => {
  return {
    ...ctx,
    content: 'content',
  }
}

async function main() {
  return await compose(addUser, addContent)({ content: '', user: '' });
}

main().then(result => {
  console.log('result', result);
});