角2加零为字符串之前数不起作用

Question

大家好我的工作时钟计时器我写在角码的代码它做工非常精细

let timer: string = "0:00:00"; 

startPause() { 
    this.play = false; 
    this.pause = true; 
    let sec = 0; 
    let min = 0; 
    let hour = 0; 

    setInterval(() => { 
    if(sec === 59) { 
     min++; 
     sec = 0; 
    } 
    else if(min > 59) { 
     hour++; 
     min = 0; 
    } 
    else { 
     sec++; 
    } 
    this.timer = `${hour}:${min}:${sec}`; 
    }, 10); 
} 

输出是正确的，但在我想在几秒钟或几分钟或几小时前加零，如果他们是< 10我写这个sec = "0" + sec它告诉我the String Type Is Not assignable to sec谢谢你。

Answer 1

尝试这样：

... 
let strSec = String(sec); 
if (sec < 10) { 
    strSec = '0' + strSec; 
} 
... //same for hour and min 
this.timer = `${strHour}:${strSec}:${strSec}`;