vue2.0 watch

export default {
    props: {
      fatherAjaxData: {
        type: Object
      }
    },
    data() {
      return {
        a: 1,
        b: 2,
        c: 3
      }
    },
    watch: {
      // 父级异步加载的数据 props 方式给到 当前子级
      fatherAjaxData: function (val, oldVal) {
        this.$nextTick(() => {
          console.log(‘监听到已异步加载的fatherAjaxData数据 已有值‘);
        });
      },
      a: function (val, oldVal) {
        console.log(`watch a val change --- new val: ${val}, old val: ${oldVal}`);
      },
      // watch_b_val_change 方法名
      b: ‘watch_b_val_change‘,
      c: {
        handler: function (val, oldVal) {
          console.log(`watch c val change --- new val: ${val}, old val: ${oldVal}`);
        },
        deep: true // 为了发现对象内部值的变化，可以在选项参数中指定 deep: true 。注意监听数组的变动不需要这么做。
      }
    },
    mounted() { // vue 生命周期方法 vue页面全部加载完毕(不包括异步数据)
      this.$nextTick(() => {
        console.log(‘vue页面加载完毕!‘);
      });
    },
    methods: {
      watch_b_val_change(val, oldVal) {
        console.log(`watch b val change --- new val: ${val}, old val: ${oldVal}`);
      }
    }
  };

vm.$watch(‘someObject‘, callback, {
  deep: true
})
vm.someObject.nestedValue = 123
// callback is fired