Vue文本框显示当前可输字数效果

<template>
  <p class="wrapper">
    <p class="parents">
      <textarea placeholder="请输入您要填写的个性签名" maxlength="30" autofocus="true" v-model="val"></textarea>
      <span class="tips">
        可输入
        <b :class="{&#39;remnant&#39;:remnant.length!=0,&#39;zero&#39;:remnant.length==0}">{{remnant}}</b>个字。
      </span>
    </p>
  </p>
</template>

<script>
export default {
  data() {
    return {
      val: "",
      maxLength: 30
    };
  },
  computed: {
    remnant() {
      return this.maxLength - this.val.length;
    }
  }
};
</script>

<style scoped>
.wrapper {
  border-top: 1px solid #999;
  padding: 30px;
}
.parents {
  width: 100%;
  height: 80px;
  position: relative;
}
textarea {
  position: absolute;
  left: 0;
  top: 0;
  width: 100%;
  height: 100%;
}
.tips {
  position: absolute;
  bottom: 0;
  right: 0;
}
.remnant {
    color: aqua;
}
.zero{
    color: #e81844;
}
</style>