el-input-number 用户清空内容如何展示默认值？Display default value after user cleared the input.

[Towry Wang]

现象：el-input-number 清空内容后，输入框展示为空，但是我们可能需要展示默认的值，比如数字 1。

解决办法：

<template>
<el-input-number  v-model="change"  step-strictly :step="1" :min="1" :max="max" @input="onAmountChange" />
</template>

<script>
export default {
  data() {
    return {
      change: 1,
    }
  },
  methods: {
    onAmountChange(value) {
      if (!this.change) {
         // el-input-number has a watcher for the value, but at this case, the value is still "1" in the component.
         // so we need let `el-input-number` knows the value changed.
         this.change = null;
         // change the value.
         this.$nextTick(() => this.change = 1 );
      }
    }
  }
}
</script>

We need let the el-input-number knows the value has changed because clear the input will not change the value, so we use nextTick to change the value.