Within the current js syntax, you can make the code looks readable with a chain or pipe with a simple function https://github.com/beenotung/tslib/blob/master/src/pipe.ts

You can even use an array if you don't need to peek the value in the middle of a chain of operations

Example:

    createChain(
      Object.entries(envars)
      .map(([key, value]) => `${key}=${value}`)
      .join(' ')
    )
      .map(keys => `$ ${keys}`)
      .map(pattern => chalk.dim(%, 'node', args.join(' ')))
      .use(line => console.log(line))

In each step, you can name the intermediate result accordingly to it's meaning, should be more readable than calling it %