Introduction Web Development using ReactJS

CONTENT
• Introduction React JS and JSX
• Component, State, Props.
• Component API, Life Cycle.
• Pros & Cos
• Demonstration

WHAT IS REACT?
• A JavaScript Library For Building User Interfaces
• Renders your UI and responds to events.
• It also uses the concept called Virtual DOM, creates an in-memory data structure
cache, enumerates the resulting differences, and then updates the browser’s
displayed DOM efficiently.
• One of the unique features of React.js is not only it can perform on the client side, but
it can also be rendered on the server side, and they can work together interoperably.

#1 Everything is a Component:
React has no…
… controllers
… directives
… templates
… global event listeners
… models
… no view models
Just Components

#2 Single Source of Truth
Traditional data flows
No framework: Any component can communicate with any other component
React: 1-way data flow

JSX
• JSX = Javascript + XML.
const element = <h1>Hello, world!</h1>;

JSX
<script>
var helloEl = React.createElement('div', { className: 'hello' }, 'Hello,
world!');
React.render(
helloEl,
document.body
);
</script>
<script type="text/jsx">
var helloEl = <div className: "hello">Hello, world!</div>;
React.render(
helloEl,
document.body
);
</script>

COMPONENT
• Components let you split the UI into independent, reusable pieces, and think about
each piece in isolation.
• Conceptually, components are like JavaScript functions. They accept arbitrary inputs
(called "props") and return React elements describing what should appear on the
screen.

COMPONENT
class TodoInput extends React.Component {
render() {
return (
<div className="form-inline">
<input className="form-control" type="text" value={this.state.content}
onChange={this.updateState}/>
</div>
);
}
}

COMPONENT - STATE
class TodoInput extends React.Component {
constructor(props) {
super(props); //Call this function because 'this' is not allowed before super().
this.state = {
content: ''
};
this.addTodo = this.addTodo.bind(this);
}
updateState(e) {
this.setState({content: e.target.value});
}
addTodo() {
// We of course not declare onSave function of this component at parent component
// Refer to: Body.jsx for more information
// We declare this onSave at mapDispatchToProps function
this.props.onSave.call(this, this.state.content, this.props.todo && this.props.todo.id || null);
this.setState({
content: ''
})
}
render() {
return (
<div className="form-inline">
<div className="form-group">
<input className="form-control" type="text" value={this.state.content}
onChange={this.updateState}/>
</div>
</div>
);
}
}

REACT COMPONENT LIFECYCLE
• React enables to create components by invoking the React.createClass() method
which expects a render method and triggers a lifecycle that can be hooked into via a
number of so called lifecycle methods.
• This short article should shed light into all the applicable functions.
• Understanding the component lifecycle will enable you to perform certain actions
when a component is created or destroyed. Further more it gives you the
opportunity to decide if a component should be updated in the first place and to
react to props or state changes accordingly.

THE LIFECYCLE -
INITIALIZATION
• Code and example here

THE LIFECYCLE -
STATE CHANGES

THE LIFECYCLE -
PROPS CHANGES

THE LIFECYCLE -
UNMOUNTING

PROS & COS OF REACT.JS
THE GOOD POINTS:
• React.js is extremely efficient
- Virtual DOM
• It makes writing Javascript easier
- React.js uses a special syntax called JSX
• It gives you out-of-the-box developer
tools
- React.js chrome extension
• It’s awesome for SEO
• UI Test Cases
THE BAD:
• React.js is only a view layer.
• Integrating React.js into a traditional
MVC framework would require some
configuration
• There is a learning curve for beginners
who are new to web development.

Why you should use React.js:
• React.js works great for teams, strongly enforcing UI and workflow patterns.
• The user interface code is readable and maintainable.
• And also, there is now a lot of demand for developers with ReactJS experience.

Introduction Web Development using ReactJS

Introduction Web Development using ReactJS

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