如何设置间隔时间？

Question

I have use following function for timer

 function startTimer(duration) {
        $rootScope.timer = duration;
        $rootScope.minute = 0;
        $rootScope.second = 0;
        $rootScope.Minutes = 0;
        $rootScope.Seconds = 0;
        setInterval(function () {
            $rootScope.minute = parseInt($rootScope.timer / 60, 10)
            $rootScope.second = parseInt($rootScope.timer % 60, 10);
            $rootScope.Minutes = $rootScope.minute < 10 ? "0" + 
            $rootScope.minute : $rootScope.minute;
            $rootScope.Seconds = $rootScope.second < 10 ? "0" + 
            $rootScope.second : $rootScope.second;
            if (--$rootScope.timer < 0) {
                $rootScope.timer = duration;
            }
        }, 1000);
    }

startTimer(300);

I am using $rootScope.Minutes and $rootScope.Seconds in view to display time. And time reduce by seconds . but if i close timer and open again it will reduce by 2 seconds. and again i close and open then it will reduce by 3 seconds. like wise iterations goes. I do not know where i did mistake. Please help me.

Answer 1

Every time you call startTimer , it will fire off another setInterval , which will run independently. Because you are using the same variables, each setInterval will operate on your $rootScope.timer variable independently.

The solution is to save a handle to the setInterval at the start, and clearInterval before setting a new interval.

function startTimer(duration) {
        $rootScope.timer = duration;
        $rootScope.minute = 0;
        $rootScope.second = 0;
        $rootScope.Minutes = 0;
        $rootScope.Seconds = 0;

        // modified bit
        if($rootScope.internvalhandle) clearInterval($rootScope.internvalhandle);

        $rootScope.internvalhandle = setInterval(function () {
            $rootScope.minute = parseInt($rootScope.timer / 60, 10)
            $rootScope.second = parseInt($rootScope.timer % 60, 10);
            $rootScope.Minutes = $rootScope.minute < 10 ? "0" + 
            $rootScope.minute : $rootScope.minute;
            $rootScope.Seconds = $rootScope.second < 10 ? "0" + 
            $rootScope.second : $rootScope.second;
            if (--$rootScope.timer < 0) {
                $rootScope.timer = duration;
            }
        }, 1000);
    }

startTimer(300);