parse date with format

parseDate.js

function parseDate(date,format) {
    var year=0,month=0,day=0,hour=0,minute=0,seconds=0;
    function toNumber(n){
        if(n == ''){
            return -1;
        }
        return Number(n);
    }
    function yearSetter(y,p){
        if(y<1000){
            y+=2000;
        }else if(y<1899){
            return false;
        }
        year = y;
        return true;
    }
    function monthSetter(m,p){
        if(m<1||m>12){
            return false;
        }
        month = m-1;
        return true;
    }
    function daySetter(d,p){
        if(d<1||d>31){
            return false;
        }
        day = d;
        return true;
    }
    function hourSetter(h,p){
        if(h<0||h>23){
            return false;
        }
        hour=h;
        return true;
    }
    function minuteSetter(m,p){
        if(m<0||m>59){
            return false;
        }
        minute=m;
        return true;
    }
    function secondsSetter(s,p){
        if(s<0||s>59){
            return false;
        }
        seconds=s;
        return true;
    }
    var setterMap = {
        "y":yearSetter,
        "yy":yearSetter,
        "yyy":yearSetter,
        "yyyy":yearSetter,
        "M":monthSetter,
        "MM":monthSetter,
        "d":daySetter,
        "dd":daySetter,
        "h":hourSetter,
        "hh":hourSetter,
        "H":hourSetter,
        "HH":hourSetter,
        "m":minuteSetter,
        "mm":minuteSetter,
        "s":secondsSetter,
        "ss":secondsSetter
    };

    var split='-';
    var length = format.length;
    for (var index = 0; index < length; index++) {
        var element = format[index];
        if(setterMap[element]) continue;
        if(date.indexOf(element)>=0){
            date=date.replace(element,split);
            format=format.replace(element,split);
        }
    }
    var formatArray = format.split(split);
    var dateArray = date.split(split);

    for(var i=0;i<formatArray.length;i++){
        var part=formatArray[i];
        if(!part) continue;
        var setter = setterMap[part];
        if(setter){
            var num = toNumber(dateArray[i]);
            if(num>=0){
               if(setter(num,part)){
                   continue;
               }
            }
        }
        return null;
    }
    return new Date(year,month,day,hour,minute,seconds);
}
var f="dd-MM-yyyy hh:mm:ss";
var d="31-7-17 0:59:59";
var date = parseDate(d,f);
var y= date.getFullYear();
var m= date.getMonth();
var d= date.getDate();
var h= date.getHours();
var min= date.getMinutes();
var s= date.getSeconds();