<div id="app">
        <input placeholder="str" v-model='str'>
        <p>{{ getStr }} </p>
        <button type="button" v-on:click='btnClick' >獲取</button>
    </div>

<script type="text/javascript">
var vm= new Vue({
        el: '#app',
        data: {
            str: '初始值'
 
,
            getStr: null,
        },
        created: function() {
            // the created hook is called after the instance is created
        },
        computed: {
        },
        methods: {
            btnClick: function() {
                this.getStr = this.str.toUpperCase();
            },
        }
    })
</script>