git checkout step4

• using Life-cycle events

• Find filter state inside App component - it reflects search string from Header
• Pass it to the Bookshelf

In the Bookshelf we need to filter books list, but doing it in the render is huge overhead.

For this purpose exists componentWillReceiveProps lyfe-cycle event.

• Initialize state for Bookshelf with books (constructor, props; see App.js)
• Override componentWillReceiveProps for Bookshelf and filter received books with received filter. Put results to state (You don't need to use setState)

Finally typing text in search field should filter books

####step 1

• making a react simple component
• making a react component
• jsx basics
• components props

####step 2

• component lists
• props validation
• using dynamic class

####step 3

• using events
• using component state
• using dynamic local style