title: Why Redux.js launches reducer function multiple times on init?
body: <p>Learning Redux.js and building a demo app.</p>
  
  <p>I have a reducer set like this:</p>
  
  <pre><code>// Imports here
  function blocksFunc(state = [], action) {
  
    switch (action.type) {
  
    case 'ADD_BLOCK':
  
      _id++;
      return [...state, {'_class' : 'basic', '_id' : _id }];
  
    default:
  
      state = []; 
      return state;
    }
  }
  
  const BlockGeneratorReducer = combineReducers({
  
    blocksFunc,
  });
  
  export default BlockGeneratorReducer;
  </code></pre>
  
  <p>I successfully update the state, but when logging I get the following when page loads:</p>
  
  <blockquote>
    <p>blocksFunc() type: "@@redux/INIT"</p>
    
    <p>blocksFunc() type:
    "@@redux/PROBE_UNKNOWN_ACTION_b.f.4.q.y.o.a.v.2.t.9"</p>
    
    <p>blocksFunc() type: "@@redux/INIT"</p>
  </blockquote>
  
  <p>So blocksFunc function is launched three times with default action.type. On which occasions is the action type "@@redux/INIT" launched? What might "@@redux/PROBE_UNKNOWN_ACTIOM" refer in to?</p>
  
  <p>The full source can be found on git: <a href="https://github.com/JaakkoKarhu/redux-react-blockgenerator">https://github.com/JaakkoKarhu/redux-react-blockgenerator</a></p>
  
  <p>The working demo is uploaded to my server: <a href="http://jaakkokarhu.com/playground/redux-block-generator/">http://jaakkokarhu.com/playground/redux-block-generator/</a></p>
  
  <p>Since being new with React and Redux, all the other comments regarding the source are also very welcome.</p>
  
  <p>EDIT:</p>
  
  <p>blocksFunc() edited according to DavidWalshes advice.</p>