js获计算时间差取年份

//传递开始、结束时间计算设置值
function SetCompanyAge() {
    var startDateStr = DLMISForm_GetControl("HR_BasicInfo", "StartWork", -1).value;//入职时间
    var endDateStr = getNowFormatDate();//当前时间
    var year = getDateYearSub(startDateStr, endDateStr);
    DLMISForm_SetControl("HR_BasicInfo", "CompanyAge", -1, year);
}
//计算年份
function getDateYearSub(startDateStr, endDateStr) {
    var day = 24 * 60 * 60 *1000; 
    var sDate = new Date(Date.parse(startDateStr.replace(/-/g, "/")));
    var eDate = new Date(Date.parse(endDateStr.replace(/-/g, "/")));

    //得到前一天(算头不算尾)
    sDate = new Date(sDate.getTime() - day);

    //获得各自的年、月、日
    var sY  = sDate.getFullYear();     
    var sM  = sDate.getMonth()+1;
    var sD  = sDate.getDate();
    var eY  = eDate.getFullYear();
    var eM  = eDate.getMonth()+1;
    var eD  = eDate.getDate();

    if(eY > sY && sM == eM && sD == eD) {
        return eY - sY;
    } else {
        //alert("两个日期之间并非整年，请重新选择");
        return 0;
    }
}
//获取当前时间
function getNowFormatDate() {
        var date = new Date();
        var seperator1 = "-";
        var year = date.getFullYear();
        var month = date.getMonth() + 1;
        var strDate = date.getDate();
        if (month >= 1 && month <= 9) {
            month = "0" + month;
        }
        if (strDate >= 0 && strDate <= 9) {
            strDate = "0" + strDate;
        }
        var currentdate = year + seperator1 + month + seperator1 + strDate;
        return currentdate;
    }