Vuejs --04 计算属性

<div id="example">
{{ message.split(‘‘).reverse().join(‘‘) }}
</div>

<div id="app">
     你好{{ ComMessage }}
     <p>{{ ComMsg() }}</p>
</div>
 
 
var vm = new Vue({
     el: ‘#app‘,
     data: {
          message: ‘hello world‘
     },
     computed: {
          ComMessage: function(){
               return this.message.split(‘‘).reverse().join(‘‘);     //this 指向vm实例
          }
     },
     method: {
          ComMsg: function(){
               return this.message.split(‘‘).reverse().join(‘‘);     //this 指向vm实例              
          }
     }
});

//意味着下面的计算属性将不再更新，因为 Date.now() 不是响应式依赖：
computed: {
     now: function () {
          return Date.now()
     }
}

<div id="demo">{{ fullName }}</div>
 
======================================================
var vm = new Vue({
    el: ‘#demo‘,
    data: {
        firstName: ‘Foo‘,
        lastName: ‘Bar‘,
        fullName: ‘Foo Bar‘
    },
    watch: {
        firstName: function(val) {
            this.fullName = val + ‘ ‘ + this.lastName
        },
        lastName: function(val) {
            this.fullName = this.firstName + ‘ ‘ + val
        }
    }
})
 
=======================================================
var vm = new Vue({
    el: ‘#demo‘,
    data: {
        firstName: ‘Foo‘,
        lastName: ‘Bar‘
    },
    computed: {
        fullName: function() {
            return this.firstName + ‘ ‘ + this.lastName
        }
    }
})

// ...
computed: {
        fullName: {
            // getter
            get: function() {
                return this.firstName + ‘ ‘ + this.lastName
            },
            // setter
            set: function(newValue) {
                var names = newValue.split(‘ ‘)
                this.firstName = names[0]
                this.lastName = names[names.length - 1]
            }
        }
    }
    // ...