function aa() {

            var OldArray = [];
            OldArray[0] = "a";
            OldArray[1] = "1";
            OldArray[2] = "5";
            OldArray[3] = "3";
            OldArray[4] = "b";
            OldArray[5] = "6";
            OldArray[6] = "2";
            OldArray[7] = "a";
            debugger;
            var NewArray = [];
            for (var i = 0; i < OldArray.length; i++) {
                if (!isNaN(OldArray[i])) {
                    if (Number(OldArray[i]) > 3) {
                        NewArray[Number(NewArray.length)] = OldArray[i];
                    }
                }
            }
            var str = "";
            for (var i = 0; i < NewArray.length; i++) {
                str += ("-" + NewArray[i])
            }
            alert(str);
        }

------解决方案--------------------

JScript code
  var OldArray =['a', 1, 5, 3, 'b', 6, 2, 7];
            var NewArray = [];
            var pattern = /\d+/;
            for (var i in OldArray) {
                if (pattern.test(OldArray[i])) {
                    if (OldArray[i] >3) {
                        NewArray.push(OldArray[i]);
                    }
                }
            }