휴대폰번호 검사

<SCRIPT LANGUAGE="JavaScript">
<!--
function maskHp(obj) {
    var str = obj.value;
    if ( str ) {
        //var pattern = /[^(ㄱ-&#55203;)]|[-/\s]/g;
        var RegNotNum  = /[\D]/g;
        var pattern = "";
        var format   = "";

        // delete not number ㅋ
        str = str.replace(RegNotNum,'');

        //if( str.length < 4 ) return str;
        if( str.length < 4 ) {
            if( str.length == 3 ) {
                format = "$1";
                pattern = /(^01[\d]{0,1})/;
            } else {
                format = "$1";
                pattern = /(^0[1]?[\d]{0,1})/;
            }
        } else if( str.length > 3 && str.length < 7 ) {
            format = "$1-$2";
            pattern = /(^01[\d]{1})([\d]+)/;
        } else if(str.length == 7 ) {
            format = "$1-$2";
            pattern = /(^01[\d]{1})([\d]{4})/;
        } else {
            format = "$1-$2-$3";
            pattern = /(^01[\d]{1})([\d]{4})([\d]+)/;
        }

        //while( pattern.test(str) ) {
        if ( pattern.test(str) ) {
            obj.value = str.replace(pattern, format);
        } else {
            obj.value = "";
        }
    }
}

function isHpFormat() {
  var str = window.event.srcElement.value;
  //alert ( str );
  if ( window.event.propertyName == "value" && str ) {
        var pattern = "";
        str = str.replace(/[\D]/g,'');
        if( str.length < 4 ) {
            if( str.length == 3 ) pattern = /(^01[\d]{1})/;
            else                  pattern = /(^0[1]?[\d]{0,1})/;
        } else if( str.length > 3 && str.length < 7 ) {
            pattern = /(^01[\d]{1})([\d]+)$/;
        } else if(str.length == 7 ) {
            pattern = /(^01[\d]{1})([\d]{4})/;
        } else {
            pattern = /(^01[\d]{1})([\d]{4})([\d]+)/;
        }
        if ( pattern.test(str) ) {
            return true;
        } else {
            return false;
        }
  } else {
        return true;
      // undefined
  }
}

//-->
</SCRIPT>
<input type='text' id='phon_num' value=''
size='14' maxlength='13'
onpropertychange='if(!isHpFormat()){alert("핸드폰 번호가 정확히 입력해주세요.");this.value="";}'
onkeyup ='maskHp(this);'
onkeydown='maskHp(this);'  >