<div id="app">
 {{ message }}
</div>

<script>
var values = {message: 'Hello Vue!'}
var vm = new Vue({
 el: '#app',
 data: values
})
console.log(vm);
</script>

<script>
var values = {message: 'Hello Vue!'}
var vm = new Vue({
 el: '#app',
 data: values
})
console.log(vm.$data === values);//true
console.log(vm.message);//'Hello Vue!'
console.log(vm.$data.message);//'Hello Vue!'
</script>

<script>
var values = {
 message: 'Hello Vue!',
 _name: '小火柴'
}
var vm = new Vue({
 el: '#app',
 data: values
})
console.log(vm._name);//undefined
console.log(vm.$data._name);//'小火柴'
</script>

<div id="example">
 <p>原始字符串: "{{ message }}"</p>
 <p>反向字符串: "{{ reversedMessage }}"</p>
</div>

<script>
var vm = new Vue({
 el: '#example',
 data: {
 message: '小火柴'
 },
 computed: {
 reversedMessage: function () {
  return this.message.split('').reverse().join('')
 }
 }
})
</script>

console.log(vm.reversedMessage) // -> '柴火小'
vm.message = 'Goodbye'
console.log(vm.reversedMessage) // -> 'eybdooG'

<script>
var vm = new Vue({
 data: { a: 1 },
 computed: {
 // 仅读取，值只须为函数
 aDouble: function () {
  return this.a * 2
 },
 // 读取和设置
 aPlus: {
  get: function () {
  return this.a + 1
  },
  set: function (v) {
  this.a = v - 1
  }
 }
 }
})
console.log(vm.aPlus);//2
vm.aPlus = 3
console.log(vm.a);//2
console.log(vm.aDouble);//4
</script>

<div id="example">
 <p>原始字符串: "{{ message }}"</p>
 <p>反向字符串: "{{ reversedMessage() }}"</p>
</div>

<script>
var vm = new Vue({
 el: '#example',
 data: {
 message: '小火柴'
 },
 methods: {
 reversedMessage: function () {
  return this.message.split('').reverse().join('')
 }
 } 
})
</script>

<div id="example">
 <p>计算属性: "{{ time1 }}"</p>
 <p>methods方法: "{{ time2() }}"</p>
</div>

<script>
var vm = new Vue({
 el: '#example',
 computed:{
 time1: function () {
  return (new Date()).toLocaleTimeString()
 }
 },
 methods: {
 time2: function () {
  return (new Date()).toLocaleTimeString()
 }
 } 
})
</script>

<div id="app">
 <button @click="a++">a加1</button>
 <p>{{ message }}</p>
</div>

<script>
var vm = new Vue({
 el: '#app',
 data: {
 a: 1,
 message:''
 },
 watch: {
 a: function (val, oldVal) {
  this.message = 'a的旧值为' + oldVal + '，新值为' + val;
 }
 }
})
</script>

<div id="app">
 <button @click="a++">a加1</button>
 <p>{{ message }}</p>
</div>

<script>
var vm = new Vue({
 el: '#app',
 data: {
 a: 1,
 message:''
 }
})
var unwatch = vm.$watch('a',function(val, oldVal){
 if(val === 10){
 unwatch();
 }
 this.message = 'a的旧值为' + oldVal + '，新值为' + val; 
})
</script>