/**
 * 日期转时间戳
 * @param {String} time - 日期字符串，如'2018-8-8','2018,8,8','2018/8/8'
 * @returns {Number} 返回值为时间毫秒值
 */
function timeToTimestamp (time) {
    let date = new Date(time);
    let timestamp = date.getTime();
    return timestamp;
}