ReactJS FAQ’s

Limitations of React are :

• It can be little difficult for the novice programmers to understand
• Coding gets complex as it uses inline templating and JSX
• React is just a library, not a full-blown framework.
• Its library is very large and takes time to understand.

Props is the shorthand for Properties in React. They are read-only components which must be kept immutable. They are always passed down from the parent to the child components throughout the application. A child component cannot send a prop back to the parent component. This helps in maintaining the unidirectional data flow and they are generally used to render the dynamically generated data.

States are the heart of React components. They are the source of data and must be kept as simple as possible. States are the objects which determine components rendering and behavior. They are mutable unlike the props and create dynamic and interactive components. They are accessed via this.state().

Synthetic events combine the response of different browser's native events into one API, ensuring that the events are consistent across different browsers.

The application is consistent regardless of the browser it is running in. Here, preventDefault is a synthetic event.

We can implement routing in React application by considering that have the components App, About, and Contact in our application.

HOC can be used for many tasks such as

• Render High jacking
• Code reuse, logic and bootstrap abstraction
• Props manipulation
• State abstraction and manipulation

Flux is the application architecture which Facebook uses for the building of web applications. It is a process of handling complex data inside a client-side application and manages how data flows in a React application.

Pure components are the simplest and fastest components which can be written. They can replace any component which only has a render(). These components enhance the simplicity of the code and performance of the application.

React Router is a routing library built on top of React, which is used to create routes in a React application.

Keys are used for identifying unique Virtual DOM Elements with their corresponding data driving the UI. They help React to optimize the rendering by recycling all the existing elements in the DOM. These keys must be a unique number or string, using which React just reorders the elements instead of re-rendering them. This leads to increase in application’s performance.

React Router maintains consistent structure and behavior and is used to develop a single-page web applications. It  enables multiple views in a single application by defining multiple routes in the React application.

The major problems with MVC framework :

• Applications were slow and inefficient
• DOM manipulation was very expensive
• There was huge memory wastage
• Due to circular dependencies, a complicated model was created around models and views

React forms are similar to HTML forms. But in React, the state is contained in the state property of the component and is only updated via setState(). Thus the elements can’t directly update their state and their submission is handled by a JavaScript function. This function has full access to the data that is entered by the user into a form.

In React, it is necessary to start component names with a capital letter. If we start the component name with small letter or lower case, it will throw an error as an unrecognized tag. It is because, in JSX, lower case tag names are considered as HTML tags.