requestAnimationFrame

function animationFrame() {
    var preTimeStamp = new Date().getTime()
    var fpsInterval = 1000
    return function animation() {       // 执行时的时间
        var now = new Date().getTime();
        var elapsed = now - preTimeStamp;
        // 经过了足够的时间
        if (elapsed > fpsInterval) {
            preTimeStamp = now - (elapsed % fpsInterval); //校正当前时间
            checkReward()
        }
        requestAnimationFrame(animation);
    }
}
var startAnimation = animationFrame();
startAnimation()