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Comment by kwxza | Hacker News Reader

Forgive me for this simple and unrelated question, but I'm new to JS development. This line right here, what is this?

let courseId = fields.to.substring(0, fields.to.indexOf('@'));

I've never seen this 'to' string method and I can't find a doc page for it. Can you explain it or point me towards a reference? Thanks

I haven't read the article, but there's no special significant to the `to` here. It is just looking up the value of a key named `to` in an object called `fields`, using [dot notation](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Refe...):

  const fields = {
    to: "foo@bar.com"
  };

  fields.to  // "foo@bar.com