其他---10watch监听

01.this.$watch

    // 用法一：  
　　this.$watch("要监听的值",(oldVal,newVal)=>{ })

    this.$watch("name", (newValue, oldValue) => {
      console.log(newValue + "_新值");
      console.log(oldValue + "_旧值");
    });

    //这样监听不到对象的变化的
    this.$watch("obj", (newval, oldval) => {
      console.log(newval);
      console.log(oldval);
    });

02.watch

  watch: {
    age: (newValue, oldValue) => {
      console.log(newValue);
      console.log(oldValue);
    },

    // 监听对象中的某个属性的变化
    "obj.id":(newVal,oldVal)=>{
      console.log(newVal);
      console.log(oldVal);
    　　}
　　}

03.深度监听

   //深度监听
    obj:{
      handler(newVal,oldVal){
        console.log(newVal);
        console.log(oldVal);
        
      },