checkbox-agree

index.html

<div id="app">
  <input type="checkbox" id="check" v-model="agree">
  <label for="check">agree</label>
  <h1>{{agree}}</h1>
  <button @click="submit">submit</button>
</div>

script.js

new Vue({
  el:'#app',
  data:{
    agree: false,
  },
  methods:{
    submit(e){
      if(this.agree !== true){
        alert(" agree!!!!!!!!!");
        return;
      }
    }
  }
})