跳目录进度条不会变化，找了好久没找到解决办法

getCurProgress: function(type){
    var currentLocation = vm.rendition.currentLocation();
    if (type=='prev') {
        vm.progress = (Math.floor(vm.locations.percentageFromCfi(currentLocation.start.cfi)*10000)/100).toFixed(0);
    }
    if (type=='next') {
        vm.progress = (Math.floor(vm.locations.percentageFromCfi(currentLocation.start.cfi)*10000)/100).toFixed(0);
    }else {
        vm.progress = (Math.floor(vm.locations.percentageFromCfi(currentLocation.start.cfi)*10000)/100).toFixed(0);
    }
    this.$refs.progress.style.backgroundSize = `${vm.progress}% 100%`;
},