input[type=tel] {
 opacity: 0;
 z-index: -1;
 position: absolute;
 left:-100%;
}

input[type=tel] {
 width: 0.1px;
 height: 0.1px;
 color: transparent;
 position: relative;
 top: 23px;
 background: #000000;
 left: 46px;
 border: none;
 font-size: 18px;
 opacity: 0;
 z-index: -1;
}

<template>
 <div id="payPwd">
  <header>支付密码设置</header>
  <input ref="pwd" type="tel" maxlength="6" v-model="msg" class="pwd" unselectable="on" />
  <ul class="pwd-wrap" @click="focus">
   <li :class="msg.length == 0"><i v-if="msg.length > 0"></i></li>
   <li :class="msg.length == 1"><i v-if="msg.length > 1"></i></li>
   <li :class="msg.length == 2"><i v-if="msg.length > 2"></i></li>
   <li :class="msg.length == 3"><i v-if="msg.length > 3"></i></li>
   <li :class="msg.length == 4"><i v-if="msg.length > 4"></i></li>
   <li :class="msg.length == 5"><i v-if="msg.length > 5"></i></li>
  </ul>
  <button type="button" @click="sendCode">获取验证码 lodding</button>
 </div>
</template>
<script>
 import api from "./api";
 import "@/js/utils"; //公共方法
 export default {
  components: {},
  data() {
   return {
    msg: '',
   }
  },
  created() {},
  computed: {},
  watch: {
   msg(curVal) {
    if(/[^\d]/g.test(curVal)) {
     this.msg = this.msg.replace(/[^\d]/g, '');
    }
   },
  },
  methods: {
   focus() {
    this.$refs.pwd.focus();
   },
   sendCode() {
    //时间
    utils.sendCode(event.target);

    //showLoading
    utils.view.showLoading();

    setTimeout(function() {
     utils.view.dismissLoading();
    }, 5000);
   }
  },
  mounted() {}
 }
</script>
<style lang="less" scoped>
 #payPwd {
  height: auto;
  header {
   text-align: center;
   height: 80px;
   line-height: 90px;
   text-align: center;
  }
  input[type=tel] {
   width: 0.1px;
   height: 0.1px;
   color: transparent;
   position: relative;
   top: 23px;
   background: #000000;
   left: 46px;
   border: none;
   font-size: 18px;
   opacity: 0;
   z-index: -1;
  }
  //光标
  .psd-blink {
   display: inline-block;
   background: url("./img/blink.gif") no-repeat center;
  }
  .pwd-wrap {
   width: 90%;
   height: 50px;
   padding-bottom: 1px;
   margin: 0 auto;
   background: #fff;
   border: 1px solid #ddd;
   display: flex;
   display: -webkit-box;
   display: -webkit-flex;
   cursor: pointer;
   position: absolute;
   left: 0;
   right: 0;
   top: 13%;
   z-index: 10;
   li {
    list-style-type: none;
    text-align: center;
    line-height: 50px;
    -webkit-box-flex: 1;
    flex: 1;
    -webkit-flex: 1;
    border-right: 1px solid #ddd;
    &:last-child {
     border-right: 0;
    }
    i {
     height: 10px;
     width: 10px;
     border-radius: 50%;
     background: #000;
     display: inline-block;
    }
   }
  }
  button {
   position: relative;
   display: block;
   height: 41px;
   text-align: center;
   margin: 0 auto;
   margin-top: 70%;
   padding: 0 20px;
   border-radius: 5px;
   font-size: 16px;
   border: 1px solid #dddddd;
   background: #dddddd;
   color: #000000;
  }
 }
</style>

//去掉 :class="msg.length == 0" 即可
<li><i v-if="msg.length > 0"></i></li>