Impure Action Creator

impure-action-creator.js

// Action creators can be impure.
export const addChat = ({
  // cuid is safer than random uuids/v4 GUIDs
  // see usecuid.org
  id = cuid(),
  msg = '',
  user = 'Anonymous',
  timeStamp = Date.now()
} = {}) => ({
  type: ADD_CHAT,
  payload: { id, msg, user, timeStamp }
});

{
  // cuid is safer than random uuids/v4 GUIDs
  // see usecuid.org
  id = cuid(),
  msg = '',
  user = 'Anonymous',
  timeStamp = Date.now()
} = {}

What does the } = {} do? I'm a bit confused about that. It seems like it just makes the first object an empty object {}.

The first "object" is deconstructing and setting defaults on the single first argument given. Which is itself given a default of an object as a default after the } =.

So this function expects a single param which is an object containing id, msg, user, and timestamp. If the object is not given (aka the function runs with only undefined as an argument or no argument. Then the first argument will default to an empty object... out of which the first "object" will be deconstructed for each value of or set with a default.

So addChat() is the same as

addChat({ id: cuid(), msg: "", user: "Anonymous", timestamp: ${currentTime()} })

But if user is given it will use the user or if msg is originally included in the argument given-- it will use the msg originally given:

addChat({ id: cuid(), msg: "blah blah", user: "me@me.com", timestamp: ${currentTime()} })