<input v-model="sth" />
<input v-bind:value="sth" v-on:input="sth = $event.target.value" />

<input :value="sth" @input="sth = $event.target.value" />

<div id="demo">
 <currency-input v-model="price"></currentcy-input>
 <span>{{price}}</span>
</div>
<script src="https://cdn.bootcss.com/vue/2.3.0/vue.js"></script>
<script>
Vue.component('currency-input', {
 template: `
  <span>
   <input
    ref="input"
    :value="value"
    <!--为什么这里把 'input' 作为触发事件的事件名？`input` 在哪定义的？-->
    @input="$emit('input', $event.target.value)"
   >
  </span>
 `,
 props: ['value'],// 为什么这里要用 value 属性，value在哪里定义的？貌似没找到啊？
})

var demo = new Vue({
 el: '#demo',
 data: {
  price: 100,
 }
})
</script>

<currency-input v-model="price"></currentcy-input>
<!--上行代码是下行的语法糖
 <currency-input :value="price" @input="price = arguments[0]"></currency-input>
-->

<input type="checkbox" v-model="sth" />

<input type="checkbox" :checked="status" @change="status = $event.target.checked" />

<my-checkbox v-model="foo"></my-checkbox>

Vue.component('my-checkbox', {
 tempalte: `<input 
        type="checkbox"
        @change="$emit('input', $event.target.checked)"
        :checked="value"
       />`
 props: ['value'],
})

<my-checkbox v-model="foo"></my-checkbox>

Vue.component('my-checkbox', {
 tempalte: `<input 
        type="checkbox"
        <!--这里就不用 input 了，而是 balabala-->
        @change="$emit('balabala', $event.target.checked)"
        :checked="value"
       />`
 props: ['checked'], //这里就不用 value 了，而是 checked
 model: {
  prop: 'checked',
  event: 'balabala'
 },
})