[Bug Report]select 组件 on-clear事件赋值undefined问题

[yangxuehua]

Environment

win10/chrome/vue2.6

Reproduction link

https://run.iviewui.com/ccTn8KU4

Steps to reproduce

在select组件上加上onclear，并在响应方法中对v-model的变量赋一个字符串常值，最后点“提交”针对此变量进行打印，显示undefined

What is expected?

变量要是显示成此前赋过的值

What is actually happening?

undefined

[es5es5]

SAME ISSUE...!

I faced this problem too, please fix this issue.

I expect just '' but return undefined.

[CT66]

升级到4.3.0。开启clearable 属性后依旧还是返回undefined，而不是“”

[icarusion]

v-model 必须指定已存在Option的，且在 nextTick