ReactN: addCallback Example

reactn.addCallback.js

import { addCallback, setGlobal } from 'reactn';

// Every time the global state changes, this function will execute.
function prevent1(newGlobalState) {
  alert(`The new value is ${newGlobalState.value}!`);

  // If the global state was changed to 1, change it to 2.
  if (newGlobalState.value === 1) {
    return { value: 2 };
  }
}
addCallback(prevent1);

setGlobal({ value: 1 });
// The new value is 1!
// The new value is 2!