In this blog, we will explain React component API. We will discuss three methods: setState(), forceUpdate and ReactDOM.findDOMNode(). In new ES6 classes, we have to manually bind this. We will use this.method.bind(this) in the examples.

Set State

setState() method is used to update the state of the component. This method will not replace the state, but only add changes to the original state.

import React from 'react';

class App extends React.Component {
constructor() {
super();

this.state = {
data: []
}

this.setStateHandler = this.setStateHandler.bind(this);
};
setStateHandler() {
var item = "setState..."
var myArray = this.state.data.slice();
myArray.push(item);
this.setState({data: myArray})
};
render() {
return (
<div>
<button onClick = {this.setStateHandler}>SET STATE</button>
<h4>State Array: {this.state.data}</h4>
</div>
);
}
}
export default App;

We started with an empty array. Every time we click the button, the state will be updated. If we click five times, we will get the following output.

Force Update

Sometimes we might want to update the component manually. This can be achieved using the forceUpdate() method.

import React from 'react';

class App extends React.Component {
constructor() {
super();
this.forceUpdateHandler = this.forceUpdateHandler.bind(this);
};
forceUpdateHandler() {
this.forceUpdate();
};
render() {
return (
<div>
<button onClick = {this.forceUpdateHandler}>FORCE UPDATE</button>
<h4>Random number: {Math.random()}</h4>
</div>
);
}
}
export default App;

We are setting a random number that will be updated every time the button is clicked.

Find Dom Node

For DOM manipulation, we can use ReactDOM.findDOMNode() method. First we need to import react-dom.

import React from 'react';
import ReactDOM from 'react-dom';

class App extends React.Component {
constructor() {
super();
this.findDomNodeHandler = this.findDomNodeHandler.bind(this);
};
findDomNodeHandler() {
var myDiv = document.getElementById('myDiv');
ReactDOM.findDOMNode(myDiv).style.color = 'green';
}
render() {
return (
<div>
<button onClick = {this.findDomNodeHandler}>FIND DOME NODE</button>
<div id = "myDiv">NODE</div>
</div>
);
}
}
export default App;

The color of myDiv element changes to green, once the button is clicked.

Note − Since the 0.14 update, most of the older component API methods are deprecated or removed to accommodate ES6.
So, this brings us to the end of blog. This Tecklearn ‘ReactJS – Component API’ blog helps you with commonly asked questions if you are looking out for a job in React JS and Front-End Development. If you wish to learn React JS and build a career in Front-End Development domain, then check out our interactive, React.js with Redux Training, that comes with 24*7 support to guide you throughout your learning period.

React.js with Redux Training

About the Course

Tecklearn’s React JS Training Course will help you master the fundamentals of React—an important web framework for developing user interfaces—including JSX, props, state, and events. In this course, you will learn how to build simple components & integrate them into more complex design components. After completing this training, you will be able to build the applications using React concepts such as JSX, Redux, Asynchronous Programming using Redux Saga middleware, Fetch data using GraphQL, perform Testing using Jest, successively Deploy applications using Nginx and Docker plus build Mobile applications using React Native. Accelerate your career as a React.js developer by enrolling into this React.js training.

Why Should you take React.js with Redux Training?

• The average salary for “React Developer” ranges from $100,816 per year to $110,711 per year, based on the role (Front End Developer/Full Stack Developer) – Indeed.com
• React Native Supports Cross-platform Development (iOS and Android), and it can reduce the development effort by almost 50% without compromising quality or productivity
• Currently, React JS is being used by major companies like Walmart, Netflix, and HelloSign.

What you will Learn in this Course?

Introduction to Web Development and React.js
• Fundamentals of React
• Building Blocks of Web Application Development
• Single-page and Multi-page Applications
• Different Client-side Technologies
• MVC Architecture
• Introduction to React
• Installation of React
• JSX and its use case
• DOM
• Virtual DOM and its working
• ECMAScript
• Difference between ES5 and ES6
• NPM Modules

Components, JSX & Props
• React Elements
• Render Function
• Components
• Class Component
• Thinking In Components
• What Is JSX
• JSX Expressions
• Creating Your First Component
• Functional Components

React State Management using Redux
• Need of Redux
• Redux Architecture
• Redux Action
• Redux Reducers
• Redux Store
• Principles of Redux
• Pros of Redux
• NPM Packages required to work with Redux
• More about react-redux package
React & Redux
• The React Redux Node Package
• Provider Component
• Connecting React Components with Redux Store
• Reducer Composition
• Normalization: Points to Keep in Mind When Designing a Redux Store
• Redux Middleware

React Hooks
• Caveat of JavaScript classes.
• Functional components and React hooks
• What are React hooks?
• Basic hooks
• useState() hook
• How to write useState() hook when state variable is an array of objects
• useEffect() hook
• Fetch API data using useEffect() hook
• useContext() hook
• Rules to write React hooks
• Additional hooks
• Custom hooks

Fetch Data using GraphQL
• What is GraphQL?
• Cons of Rest API
• Pros of GraphQL
• Frontend backend communication using GraphQL
• Type system
• GraphQL datatypes
• Modifiers
• Schemas
• GraphiQL tool
• Express framework
• NPM libraries to build server side of GraphQL
• Build a GraphQL API
• Apollo client
• NPM libraries to build client side of GraphQL
• How to setup Apollo client

React Application Testing and Deployment
• Define Jest
• Setup Testing environment
• Add Snapshot testing
• Integrate Test Reducers
• Create Test Components
• Push Application on Git
• Create Docker for React Application

Introduction to React Native
• What is React Native
• Use of JSX elements With React Native
• The anatomy of a React Native application
• React Native installation and setup
• Running the app on Android Simulator and Android Device
• Working with Styles and Layout
• Connecting React Native to Redux

React with Redux Projects

Got a question for us? Please mention it in the comments section and we will get back to you.

401