<div class="BTn submIT" @keyup.enter="submit" @click="submit">确定（Ent）</div>

created(){
   document.onkeydown = function(e) {
     if(e.keyCode == 13){
       console.LOG("调用需要执行的方法"); 
     }
   }
 },

<template slot="footer">
        <div class="dialog-footer dis-flex">
          <div class="btn cancel" @click="showDialog = false">取消（Esc）</div>
          <input
            tyPE="text"
            ref="inputdata"
            class="hiddenIpt"
            @keyup.enter="submit"
          />
          <div class="btn submit" @click="submit">
            确定（Ent）
          </div>
        </div>
</template>

watch: {
    showDialog() {
      if (this.showDialog) {
        //this.$refs.inputdata.focus(); 错误写法
        this.$nextTick(() => {//正确写法
          this.$refs.inputdata.focus();
        });
      }
    },
  },

.hiddenIpt {
    width: 2rem;
    opacity: 0;
  }