JSFiddle - React, Tailwind, and code Playground

by hlim188

HTML

<!DOCTYPE html>
<html>
    <head>
        <meta charset="utf-8">
        <title>RegEx Form</title>
        <link rel="stylesheet" href="styles.css">
    </head>
    <body>
        <h1>New User Signup</h1>
        <form>

            <input type="text" name="username" placeholder="username">
            <p>Username must be alphanumeric and contains 5 - 12 characters</p>

            <input type="text" name="email" placeholder="email">
            <p>Email must be a valid address, e.g. [email protected]</p>

            <input type="password" name="password" placeholder="password">
            <p>Password must alphanumeric (@, _ and - are also allowed) and be 8 - 20 characters</p>

            <input type="text" name="telephone" placeholder="telephone">
            <p>Telephone must be a valid UK telephone number (11 digits)</p>

            <input type="text" name="slug" placeholder="profile slug">
            <p>Slug must contain only lowercase letters, numbers and hyphens and be 8 - 20 characters</p>

        </form>
        <script type="text/javascript" src="validation.js"></script>
    </body>
</html>

CSS

body{
    font-family: arial;
    color: #333;
}
h1{
    font-weight: normal;
    margin: 20px auto;
    text-align: center;
}
form{
    width: 300px;
    margin: 20px auto;
}
input{
    display: block;
    padding: 8px 16px;
    font-size: 2em;
    margin: 10px auto;
    width: 100%;
    box-sizing: border-box;
    border-radius: 10px;
    border: 3px solid #ccc;
    outline: none !important;
}

input.valid{
    border-color: green;
}
input.invalid{
    border-color: orange;
}
input + p {
    font-size: 0.9em;
    font-weight: bold;
    text-align: center;
    margin: 0 10px;
    color: orange;
    opacity: 0;
    height: 0;
}
input.invalid + p {
    opacity: 1;
    height: auto;
    margin-bottom: 20px;
}

JavaScript

// validation script here
const inputs = document.querySelectorAll('input');

const patterns = {
    telephone: /^\d{11}$/,
    username: /^[a-z\d]{5,11}$/i,
    password: /^[\w@-]{8,20}$/,
    slug: /^[a-z\d-]{8,20}$/,
    email: /^([a-z\d\.-]+)@([a-z\d-]+)\.([a-z]{2,8})(\.[a-z]{2,8})?$/
};

// validation function
function validate(field, regex){
    // console.log(regex.test(field.value));
    if(regex.test(field.value)){
        field.className = 'valid';
    } else {
        field.className = 'invalid';
    }
}

inputs.forEach((input) => {
    input.addEventListener('keyup',(e) => {
        // console.log(e.target.attributes.name.value);
        validate(e.target, patterns[e.target.attributes.name.value]);
    })
});