【前端】輸入金額時如何判斷數字合法

代碼舉例：

var onOff=false;
function repay() {
    if(onOff){
        do sth;
    }

}
$(function(){
    var maxMoney=${amount!''};
    var reg= /(^(([0-9]+\.[0-9]{1,2})|([0-9]*[1-9][0-9]*\.[0-9]{1,2})|([0-9]*[1-9][0-9]*))$)/;
    $('#userAmount').keyup(function(){
        this.value = this.value.replace(/[^\d.]/g,"");
        if(reg.test(this.value) && 0<this.value && this.value<=maxMoney){
            $('.submit1 a').css('backgroundColor','#0097ff');
            onOff=true;
        }else{
            $('.submit1 a').css('backgroundColor','#ccc');
            onOff=false;
        }
    })
})