Why are flux constants assigned null?

Question

React

Constants created with "keyMirror" are set to null

var keyMirror = require('react/lib/keyMirror');

// Define action constants
module.exports = keyMirror({
  CART_ADD: null,
  CART_REMOVE: null,
  CART_VISIBLE: null,
  SET_SELECTED: null,
  RECEIVE_DATA: null
});

Unfortunately, I can’t understand, but I want to figure out why it assigns exactly null and whether these values ​​change during operation.
Explain please =)

Answer 1

This function returns an object where all keys have the name of the key as their value, so this can be represented as

// Define action constants
module.exports = {
  CART_ADD: "CART_ADD",
  CART_REMOVE: "CART_REMOVE",
  CART_VISIBLE: "CART_VISIBLE",
  SET_SELECTED: "SET_SELECTED",
  RECEIVE_DATA: "RECEIVE_DATA"
};