<el-input type="text" id="timetext" value="00时00分00秒" readonly></el-input>
<el-button type="button" @click="start()">开始</el-button> 
<el-button type="button" @click="stop()">暂停</el-button> 
<el-button type="button" @click="Reset()">重置</el-button>

hour: 0,
minute: 59,
second: 58,
int: null,
millisecond: 0,

//重置
Reset() {
  window.clearInterval(this.int);
  this.millisecond = this.hour = this.minute = 0;
  this.second = 58;
  document.getElementById("timetext").value = "00时00分00秒";
},
 //开始
start() {
  this.int = setInterval(this.timer, 1000);
},
//计时
timer() {
  this.second++;
  if (this.second >= 60) {
     this.second = 0;
     this.minute = this.minute + 1;
   }
  if (this.minute >= 60) {
     this.minute = 0;
     this.hour = this.hour + 1;
    }
  document.getElementById("timetext").value =
    this.hour + "时" + this.minute + "分" + this.second + "秒";
}