Vue-methods,watch和computed

朱雀 2023-06-30 01:47 2阅读 0赞

# 案例 #

把firstName和lastName组合成fullName

# 为keyup事件绑定方法 #

<body>
    
        <div id="app">
            
            <input type="text" v-model="firstName" @keyup="getFullName" /> +
            <input type="text" v-model="lastName" @keyup="getFullName" /> =
            <input type="text" v-model="fullName" />
        </div>
    
        
        <script src="https://unpkg.com/vue/dist/vue.js"></script>
        <script>
    
            var vue = new Vue({ 
                el: "#app",
                data: { 
                    firstName: "",
                    lastName: "",
                    fullName: ""
                },
                methods: { 
                    getFullName: function () { 
                        this.fullName = this.firstName + this.lastName
                    }
                }
            })
        </script>
    </body>

# watch #

<body>
    
        <div id="app">
            <input type="text" v-model="firstName" /> +
            <input type="text" v-model="lastName" /> =
            <input type="text" v-model="fullName" />
        </div>
    
        
        <script src="https://unpkg.com/vue/dist/vue.js"></script>
        <script>
            var vue = new Vue({ 
                el: "#app",
                data: { 
                    firstName: "",
                    lastName: "",
                    fullName: ""
                },
                // 使用这个属性,可以监听data中指定数据的变化,然后触发watch中对应的function函数
                watch: { 
                    // 第一个参数最新的值,第二个参数旧的值
                    firstName: function (newVal, oldVal) { 
                        this.fullName = newVal + this.lastName
                    },
                    lastName: function (newVal, oldVal) { 
                        this.fullName = this.firstName + newVal
                    }
                }
            })
        </script>
    </body>

# computed #

# 总结 #

*  watch擅长处理的场景:一个数据影响多个数据
 *  computed擅长处理的场景:一个数据受多个数据影响
 *  methods里面定义的函数，是需要主动调用的，而和watch和computed相关的函数，会自动调用，完成我们希望完成的作用