Vue Js calculate Age from date of birth

<html>

<body>
    <h3>Vue Js Calculate age from given date</h3>
    <div id="app">
        <form>
            <label>Enter your birthdate:</label>
            <input type="date" v-model="birthDate" @input="calculateAge(birthDate)">
        </form>
        <p v-if="birthDate">Your age is {{ years }} years, {{ months }} months, and {{ days }} days</p>
    </div>
    <script type="module">
        const app = new Vue({
            el: "#app",
            data() {
                return {
                    birthDate: '',
                    years: null,
                    months: null,
                    days: null

};
            },

methods: {

calculateAge(birthDate) {
                    if (!birthDate) return;

const currentDate = new Date();
                    if (new Date(birthDate) > currentDate) {
                        this.birthDate = null
                        this.years = null;
                        this.months = null;
                        this.days = null;
                        alert('Invalid Date of Birth')
                    }

const diffTime = currentDate - new Date(birthDate);
                    const totalDays = Math.floor(diffTime / (1000 * 60 * 60 * 24));
                    this.years = Math.floor(totalDays / 365.25);
                    this.months = Math.floor((totalDays % 365.25) / 30.4375);
                    this.days = Math.floor((totalDays % 365.25) % 30.4375);

}
            }
        })
    </script>

</body>

</html>