Question

How to handle and bind event in React JS

Answer 1

// counter.jsx

import React, { Component } from "react";

class Counter extends Component {
  state = {
    total: 12
  };

  constructor() {
    super();
    this.totalPlus = this.totalPlus.bind(this);
  }

  totalPlus() {
    console.log(this);
  }

  render() {
    return (
      <React.Fragment>
        <span className={this.setStyle()}>
          Render Dynamically With bootstrap.css: {this.getTotal()}
        </span>
        <button onClick={this.totalPlus} className="btn btn-secondary btn-sm">
          +
        </button>
      </React.Fragment>
    );
  }

  setStyle() {
    let classes = "badge m-2 badge-";
    classes += this.state.total === 0 ? "warning" : "primary";
    return classes;
  }

  getTotal() {
    const { total } = this.state;
    return total === 0 ? "Zero" : total;
  }
}

export default Counter;

// index.js 

import React from 'react';
import ReactDOM from 'react-dom';
import './index.css';
import App from './App';
import * as serviceWorker from './serviceWorker';
import 'bootstrap/dist/css/bootstrap.css';
import Counter from './components/counter'


ReactDOM.render( 
  <Counter />,
  document.getElementById('root')
);

serviceWorker.unregister();




/*
run:

Counter {props: {…}, context: {…}, refs: {…}, updater: {…}, state:

*/

 

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Answer 2

// counter.jsx

import React, { Component } from "react";

class Counter extends Component {
  state = {
    total: 12
  };

  // Bind with arrow function
  totalPlus = () => {
    console.log(this);
  }

  render() {
    return (
      <React.Fragment>
        <span className={this.setStyle()}>
          Render Dynamically With bootstrap.css: {this.getTotal()}
        </span>
        <button onClick={this.totalPlus} className="btn btn-secondary btn-sm">
          +
        </button>
      </React.Fragment>
    );
  }

  setStyle() {
    let classes = "badge m-2 badge-";
    classes += this.state.total === 0 ? "warning" : "primary";
    return classes;
  }

  getTotal() {
    const { total } = this.state;
    return total === 0 ? "Zero" : total;
  }
}

export default Counter;

// index.js 

import React from 'react';
import ReactDOM from 'react-dom';
import './index.css';
import App from './App';
import * as serviceWorker from './serviceWorker';
import 'bootstrap/dist/css/bootstrap.css';
import Counter from './components/counter'


ReactDOM.render( 
  <Counter />,
  document.getElementById('root')
);

serviceWorker.unregister();




/*
run:

Counter {props: {…}, context: {…}, refs: {…}, updater: {…}, state:

*/

 

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