vue-监听（watch）

watch: {
    svalue(val, oldVal) {
      if (val !== oldVal) {
        this.$emit("input", this.svalue)
      }
    }
  }

  watch: {
    form: {
      deep: true,
      handler(newval) {
        this.data = newval
      }
    }
  }

  watch: {
    ‘form.sfyx0‘: {
      deep: true,
      handler(newval) {
        this.btn= true
      }
    }
  }