vuejs checkbox all

HTML

<script src="https://unpkg.com/vue@next/dist/vue.js"></script>
<script src="https://unpkg.com/[email protected]/dist/vue.min.js"></script>
<div id="app">
<h4>User</h4>
<div>
    <table>
        <tr>
            <th><input type="checkbox" v-model="selectAll"></th>
            <th align="left">Name</th>
        </tr>
        <tr v-for="user in users">
            <td>
                <input type="checkbox" v-model="selected" :value="user.id" number>
            </td>
            <td>{{ user.name }}</td>
        </tr>
    </table>
</div>
</div>

JavaScript

new Vue({
    el: '#app',
    data: {
        users: [ 
            { "id": "1", "name": "Shad Jast", "email": "[email protected]" },
            { "id": "2", "name": "Duane Metz", "email": "[email protected]" }, 
            { "id": "3", "name": "Myah Kris", "email": "[email protected]" }, 
            { "id": "4", "name": "Dr. Kamron Wunsch", "email": "[email protected]" }
        ],
        selected: []
    },
    computed: {
        selectAll: {
            get: function () {
                return this.users ? this.selected.length == this.users.length : false;
            },
            set: function (value) {
                var selected = [];

                if (value) {
                    this.users.forEach(function (user) {
                        selected.push(user.id);
                    });
                }

                this.selected = selected;
            }
        }
    }
});