Vue the first button click to jump out of the countdown, the second button click to jump out of the fixed data

Vue the first button clicks to jump out of the countdown, and the second button clicks to jump out of the fixed data, but the data that pops out suddenly jumps back to the automatic countdown
clipboard.png

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var app = new Vue ({

el:"-sharpapp",
data:{
        items: [
            {day: "   ", hour: "   ", minute: "   ", second: "   "}
        ]

},

methods: {

    format: function (n) {
        return n < 10 ? "0" + n : n;
    },
    getMyTime: function () {
        var startDate = new Date();
        var endDate = new Date("2018/3/31 11:10:00");
        var countDown = parseInt(endDate.getTime() - startDate.getTime()) / 1000;
        var time1=countDown;
        var day = parseInt(countDown / (24 * 60 * 60));
        var h = parseInt(countDown / (60 * 60) % 24);
        var m = parseInt(countDown / 60 % 60);
        var s = parseInt(countDown % 60);
        this.items[0].day = day;
        this.items[0].hour = this.format(h);
        this.items[0].minute = this.format(m);
        this.items[0].second = this.format(s);
    },
    start: function () {
        var that = this;
        setInterval(function () {
            that.getMyTime();
        }, 1000);
    },
    change:function(){

           Vue.set(this.items,0,{
               day:2,hour:2,minute:2,second:2
           })
        clearInterval(this.items);
    }
}
})
Feb.28,2021

your clearInterval is useless at all

...
start: function () {
        var that = this;
        this.timer = setInterval(function () {
            that.getMyTime();
        }, 1000);
    },
    change:function(){
        clearInterval(this.timer);
           Vue.set(this.items,0,{
               day:2,hour:2,minute:2,second:2
           })
        
    }
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