Vue Js Name Validation

<html>
<head>
    <script src="https://cdn.jsdelivr.net/npm/vue/dist/vue.js"></script>
</head>
<body>
    <h3>Vue Js Name Validate  </h3>
    <div id="app">
        <form @submit.prevent="validateForm">
            <div>
                <label for="first-name">First Name:</label>
                <input type="text" id="first-name" v-model="firstName" />
                <pre v-if="errors.firstName" class="error">{{ errors.firstName }}</pre>
            </div>
            <br>
            <div>
                <label for="last-name">Last Name:</label>
                <input type="text" id="last-name" v-model="lastName" />
                <pre v-if="errors.lastName" class="error">{{ errors.lastName }}</pre>
            </div>
            
            <button type="submit">Submit</button>
        </form>
    </div>
    <script type="module">
        const app = new Vue({
            el: "#app",
            data() {
                return {
                    firstName: '',
                    lastName: '',
                    errors: {}
                };
            },
            methods: {
                validateForm() {
                    this.errors = {};

if (!this.firstName) {
                        this.errors.firstName = 'First name is required';
                    } else if (this.firstName.length < 2) {
                        this.errors.firstName = 'First name must be at least 2 characters long';
                    } else if (!/^[a-zA-Z]+$/.test(this.firstName)) {
                        this.errors.firstName = 'First name can only contain letters';
                    }

if (!this.lastName) {
                        this.errors.lastName = 'Last name is required';
                    } else if (this.lastName.length < 2) {
                        this.errors.lastName = 'Last name must be at least 2 characters long';
                    } else if (!/^[a-zA-Z]+$/.test(this.lastName)) {
                        this.errors.lastName = 'Last name can only contain letters';
                    }
                }
            }
        })
    </script>
    <style>
        .error {
            color: red;
        }
    </style>
</body>
</html>