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Form Validation in React JS Example



This article will give you example of react js bootstrap form validation example. you can understand a concept of react js input field validation example. This tutorial will give you simple example of reactjs form input validation. i explained simply about how to do simple form validation in react js. So, let's follow few step to create example of react js form validation example.

Form validation is a primary part of any application. we always require to add input validation when we are adding form in our application. There is a some simple validation like require, email, phone number, only number validation is almost we need to add. When ever user enter wrong value on input field then we need to display error messages.

So, here i will give you step by step instruction of how to add bootstrap form validation in react js application. in this example we will take name, email and comment input and add validation for require and email now. also display error messages if they enter wrong values.

Let's follow bellow step and you will find preview as bellow:

Preview:

Step 1: Install React App

In our first step, we need to download react js fresh app using bellow command, if you didn't install yet then.

npx create-react-app my-app

Step 2: Create DemoForm Component

In this step, we will create DemoForm.js component file and we will write code of form validation. so let's add code as bellow:

src/DemoForm.js

import React from 'react';

class DemoForm extends React.Component {

constructor() {

super();

this.state = {

input: {},

errors: {}

};

this.handleChange = this.handleChange.bind(this);

this.handleSubmit = this.handleSubmit.bind(this);

}

handleChange(event) {

let input = this.state.input;

input[event.target.name] = event.target.value;

this.setState({

input

});

}

handleSubmit(event) {

event.preventDefault();

if(this.validate()){

console.log(this.state);

let input = {};

input["name"] = "";

input["email"] = "";

input["comment"] = "";

this.setState({input:input});

alert('Demo Form is submited');

}

}

validate(){

let input = this.state.input;

let errors = {};

let isValid = true;

if (!input["name"]) {

isValid = false;

errors["name"] = "Please enter your name.";

}

if (!input["email"]) {

isValid = false;

errors["email"] = "Please enter your email Address.";

}

if (typeof input["email"] !== "undefined") {

var pattern = new RegExp(/^(("[\w-\s]+")|([\w-]+(?:\.[\w-]+)*)|("[\w-\s]+")([\w-]+(?:\.[\w-]+)*))(@((?:[\w-]+\.)*\w[\w-]{0,66})\.([a-z]{2,6}(?:\.[a-z]{2})?)$)|(@\[?((25[0-5]\.|2[0-4][0-9]\.|1[0-9]{2}\.|[0-9]{1,2}\.))((25[0-5]|2[0-4][0-9]|1[0-9]{2}|[0-9]{1,2})\.){2}(25[0-5]|2[0-4][0-9]|1[0-9]{2}|[0-9]{1,2})\]?$)/i);

if (!pattern.test(input["email"])) {

isValid = false;

errors["email"] = "Please enter valid email address.";

}

}

if (!input["comment"]) {

isValid = false;

errors["comment"] = "Please enter your comment.";

}

this.setState({

errors: errors

});

return isValid;

}

render() {

return (

<div>

<h1>React Form Validation Example - HDTuto.com</h1>

<form onSubmit={this.handleSubmit}>

<div class="form-group">

<label for="name">Name:</label>

<input

type="text"

name="name"

value={this.state.input.name}

onChange={this.handleChange}

class="form-control"

placeholder="Enter name"

id="name" />

<div className="text-danger">{this.state.errors.name}</div>

</div>

<div class="form-group">

<label for="email">Email Address:</label>

<input

type="text"

name="email"

value={this.state.input.email}

onChange={this.handleChange}

class="form-control"

placeholder="Enter email"

id="email" />

<div className="text-danger">{this.state.errors.email}</div>

</div>

<div class="form-group">

<label for="comment">Comment:</label>

<textarea

name="comment"

value={this.state.input.comment}

onChange={this.handleChange}

placeholder="Enter comment"

class="form-control" />

<div className="text-danger">{this.state.errors.comment}</div>

</div>

<input type="submit" value="Submit" class="btn btn-success" />

</form>

</div>

);

}

}

export default DemoForm;

Step 3: Import Component

In this step, we will import DemoFormcomponent in index.js main file. so let's update index.js file as bellow:

Here, i used bootstrap with react. so, if you want to use bootstrap in your app too then follow this tutorial: Install Bootstrap 4 in React JS.

src/index.js

import React from 'react';

import ReactDOM from 'react-dom';

import * as serviceWorker from './serviceWorker';

import 'bootstrap/dist/css/bootstrap.min.css';

import DemoForm from './DemoForm';

ReactDOM.render(

<React.StrictMode>

<div className="container">

<DemoForm />

</div>

</React.StrictMode>,

document.getElementById('root')

);

serviceWorker.unregister();

Now we are ready to run our application, so let's run using bellow command:

npm start

Open bellow url:

http://localhost:3000

I hope it can help you...




June 30, 2020 | Category : React



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