使用js让文本框只能输入数字 且小数保留两位

function checkNumber(e,txt)
    {
        var key = window.event ? e.keyCode : e.which;
        var keychar = String.fromCharCode(key);
        reg = /\d|\./;
        var result = reg.test(keychar);
        if(result)
            {
                if(e.keyCode==46)
                result=!(txt.value.split('.').length>1);
                else
                result=!(txt.value.split('.').length>1&&txt.value.split('.')[1].length>1);
            }
        if(!result)
            {
                
                return false;
            }
        else
        {
          
            return true;
        }
    }

调用：
onkeypress="return checkNumber(event,this);"