Vue Js Password Generator

<html>
<head>
    <script src="https://cdn.jsdelivr.net/npm/vue/dist/vue.js"></script>
</head>
<body>
    <h3>Generating Secure Passwords in Vue.js Using Only Number </h3>
    <div id="app">
        <input type="text" v-model="password" />
        <button @click="generatePassword">Generate Password</button>
    </div>
    <script type="module">
        const app = new Vue({
            el: "#app",
            data() {
                return {
                    password: ""
                };
            },
            methods: {
                generatePassword() {
                    let characters = '123456789';
                    let password = '';
                    let length = 20;

for (let i = 0; i < length; i++) {
                        password += characters.charAt(Math.floor(Math.random() * characters.length));
                    }

this.password = password;
                }
            }
        })
    </script>
    <style>
        input[type="text"] {
            width: 250px;
            height: 40px;
            font-size: 16px;
            padding: 10px;
        }

button {
            height: 40px;
            font-size: 16px;
            cursor: pointer;
        }
    </style>
</body>
</html>