Vue关于数据绑定出错解决办法

<input id="input-check" type="checkbox" v-model="toggle" v-bind:true-value="a" v-bind:false-value="b">
  <label for="input-check">check</label>
  <script type="text/javascript">
    var v = new vue({
      el: "#input-check",
      data: {
        toggle: ""
      }
    });
  </script>

 var v = new vue({
      el: "#input-check",
      data: {
        toggle: "",
        a : "a",
        b : "b"
      }
    });