React Docs

Break The UI Into A Component Hierarchy

breaking component is like dividing the component into a smaller peaces and what do we mean by that is when enter to lets say facebook wep app. you should notice that their is a navigation bar also there is the main content and thier is side bar and so on so basiclly facebook divided their app into a several component and each one of them is responsile for a several of things and this is what react.js aiding us to do it

Q1 Answer

The first thing you’ll want to do is to draw boxes around every component (and subcomponent) in the mock and give them all names. If you’re working with a designer, they may have already done this, so go talk to them! Their Photoshop layer names may end up being the names of your React components!

Single-responsibility principle

Q2 Answer

The single-responsibility principle (SRP) is a computer-programming principle that states that every module, class or function in a computer program should have responsibility over a single part of that program’s functionality, and it should encapsulate that part. All of that module, class or function’s services should be narrowly aligned with that responsibility.

Static Version in React

static component are function component which their props wont be affected changed like the state componentwhithin the state it self

Q3 Answer

To build a static version of your app that renders your data model, you’ll want to build components that reuse other components and pass data using props. props are a way of passing data from parent to child. If you’re familiar with the concept of state, don’t use state at all to build this static version. State is reserved only for interactivity, that is, data that changes over time. Since this is a static version of the app, you don’t need it.

Q4 Answer

To build your app correctly, you first need to think of the minimal set of mutable state that your app needs. The key here is DRY: Don’t Repeat Yourself. Figure out the absolute minimal representation of the state your application needs and compute everything else you need on-demand. For example, if you’re building a TODO list, keep an array of the TODO items around; don’t keep a separate state variable for the count. Instead, when you want to render the TODO count, take the length of the TODO items array

Q5 Answer

• Is it passed in from a parent via props? If so, it probably isn’t state.

• Does it remain unchanged over time? If so, it probably isn’t state.

• Can you compute it based on any other state or props in your component? If so, it isn’t state.

Q6 Answer

• For each piece of state in your application:

• Identify every component that renders something based on that state.
• Find a common owner component (a single component above all the components that need the state in the hierarchy).
• Either the common owner or another component higher up in the hierarchy should own the state.
• If you can’t find a component where it makes sense to own the state, create a new component solely for holding the state and add it somewhere in the hierarchy above the common owner component.