html部分：
<div id="app">
<all-component :is="currentpage"></all-component>
<div>
<button type="button" @click="currentpage='home'">home</button>
<button type="button" @click="currentpage='foo'">foo</button>
<button type="button" @click="currentpage='bar'">bar</button>
</div>
</div>
js部分：
var vm=new Vue({
el:"#app",
data:{currentpage:'home'},
components:{
home:{template:'<div>this is home</div>'},
foo:{template:'<div>this is foo</div>'},
bar:{template:'<div>this is bar</div>'}
}
})