表单change事件取值不生效问题

 <InputNumber v-model="edit.zj" placeholder="赠金" :min="0" style="width: 200px" @on-change="changeZj"/>

在用change 事件操作表单时，表单值不改变，js逻辑不生效，

changeZj(val) {
  this.$nextTick(() => {
     if (val == null || val == NaN) {
       val = 0
     }
     this.edit.zj = Number(parseFloat(val).toFixed(2));
     if (this.edit.zj > this.edit.mz) {
       this.edit.zj = this.edit.mz
     }
     this.edit.bj = Number(parseFloat(this.edit.mz - this.edit.zj).toFixed(2))
   })
 },

运用$nextTick 事件后运行生效