このセクションの知識点

watchメソッド動的傍受変化

app.$watch(" xxx",function(newVal,oldVal){})

コードは次のとおりです.

    
    
    


Watch option


    
    ：{{temperature}}°C
    
    :{{this.suggestion}}
    

            
            

    



    var suggestion=['T   ','    ','     '];
    var app=new Vue({
        el:'#app',
        data:{
            temperature:14,
            suggestion:'    '
        },
        methods:{
            add:function(){
                this.temperature+=5;
            },
            reduce:function(){
                this.temperature-=5;
            }
        },
        // watch:{
        //     temperature:function(newVal,oldVal){
        //         if(newVal>=26){
        //             this.suggestion=suggestion[0];
        //         }else if(newVal<26 && newVal >=0)
        //         {
        //             this.suggestion=suggestion[1];
        //         }else{
        //             this.suggestion=suggestion[2];
        //         }
        //     }
        // }

    })
    app.$watch('temperature',function(newVal,oldVal){
        if(newVal>=26){
            this.suggestion=suggestion[0];
        }else if(newVal<26 && newVal >=0)
        {
            this.suggestion=suggestion[1];
        }else{
            this.suggestion=suggestion[2];
        }

    })