js驗證開頭不為零的正整數

WST.zhengZhengShuIn = function (className){
    var rex = /^[1-9]{1}[0-9]*$/;//正整數
    $("."+className).keyup(function(event){
        var event = event || window.event;
        var value = $(this).val();
        if(value.length>1){
            var flagRex =/^0/;
            if(flagRex.test(value)){
                layer.msg('首個字符不能為0',{time:1500});
                $(this).val('');
            }
        }
    });
    $("."+className).keypress(function(event){
        var event = event || window.event;
        if (event.charCode == 46 && event.charCode !== 0 && event.charCode < 48 || event.charCode > 57) {
            return false;
        }
        if (/\./.test($(this).val()) && event.charCode === 46) {
            return false;
        }
        if ($(this).val() === "" && event.charCode === 46) {
            return false;
        }
        var tails = ($(this).val()).split(".")[1];
        if (tails && tails.length === 2 && event.charCode !== 0) {
            return false;
        }
    });

}