let mainVideo = $('video')[0]
/*加载进度*/
function loadbar() {
    if (mainVideo.readyState === 4) {
        let bufferIndex = mainVideo.buffered.length;
        if (bufferIndex > 0 && mainVideo.buffered != undefined) {
            let bufferValue = mainVideo.buffered.end(bufferIndex - 1) / mainVideo.duration * 进度条总长度;
            $('.load').width(parseInt(bufferValue) + 'px');
            if (Math.abs(mainVideo.duration - mainVideo.buffered.end(bufferIndex - 1)) < 1) {
                $('.load').width(进度条总长度 + 'px');
            }
        }
    }
}