Validating User Names in React Native: A Practical Guide |Part 1

Introduction

User input validation is a crucial aspect of developing mobile applications. It ensures data integrity and improves user experience by providing immediate feedback. In this blog post, we’ll discuss a simple yet effective way to validate user names in a React Native application using JavaScript.

The Problem

When building forms that collect user data, such as sign-up or profile update forms, it’s important to ensure that the names entered by users do not contain any special characters. Special characters can cause issues with data storage, processing, and display.

The Solution

We’ll use a small JavaScript function to strip out any unwanted special characters from user names. This function will replace any character that is not a letter or a number with an empty string, effectively removing it from the input.

The Code

Here’s the code for the validateName function:

export const validateName = (value: string) => {
  const name = value.replace(/[`~!@#$%^&*()_|+\-=?;:'",.<>\{\}\[\]\\\/]/gi, '');
  return name;
};

How It Works

1. Regular Expression: The regular expression /[~!@#$%^&*()_|+-=?;:'",.<>{}\/]/gi` matches any character that is a special character.
2. Replace Method: The replace method replaces all occurrences of these special characters with an empty string (''), effectively removing them from the input value.

include a text input field where the user can enter their name and see the validated result in real-time.

// App.js
import React, { useState } from 'react';
import { SafeAreaView, StyleSheet, Text, TextInput, View } from 'react-native';
import { validateName } from './validators';

const App = () => {
  const [name, setName] = useState('');
  const [validatedName, setValidatedName] = useState('');

  const handleNameChange = (value: string) => {
    setName(value);
    setValidatedName(validateName(value));
  };

  return (
    <SafeAreaView style={styles.container}>
      <Text style={styles.title}>Name Validation Example</Text>
      <TextInput
        style={styles.input}
        placeholder="Enter your name"
        value={name}
        onChangeText={handleNameChange}
      />
      <View style={styles.outputContainer}>
        <Text style={styles.label}>Validated Name:</Text>
        <Text style={styles.output}>{validatedName}</Text>
      </View>
    </SafeAreaView>
  );
};

const styles = StyleSheet.create({
  container: {
    flex: 1,
    justifyContent: 'center',
    alignItems: 'center',
    padding: 16,
  },
  title: {
    fontSize: 24,
    marginBottom: 16,
  },
  input: {
    width: '100%',
    height: 40,
    borderColor: 'gray',
    borderWidth: 1,
    paddingHorizontal: 8,
    marginBottom: 16,
  },
  outputContainer: {
    alignItems: 'center',
  },
  label: {
    fontSize: 18,
  },
  output: {
    fontSize: 18,
    fontWeight: 'bold',
    color: 'blue',
  },
});

export default App;