js 输入框只允许输入数字

 function clearNoNum(obj){
            obj.value = obj.value.replace(/[^\d.]/g,"");  //清除“数字”和“.”以外的字符
            obj.value = obj.value.replace(/\.{2,}/g,"."); //只保留第一个. 清除多余的
            obj.value = obj.value.replace(".","$#$").replace(/\./g,"").replace("$#$",".");
            obj.value = obj.value.replace(/^(\-)*(\d+)\.(\d\d).*$/,‘$1$2.$3‘);//只能输入两个小数
            if(obj.value.indexOf(".")< 0 && obj.value !=""){//以上已经过滤，此处控制的是如果没有小数点，首位不能为类似于 01、02的金额
                obj.value= parseFloat(obj.value);
            }
        }

 <li class="clear fl pdd">
            <span class="tips2"><span class="red" style="padding-left: 0;">*</span>金额:&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp</span>
            <p class="Long_mr gray input clear">
                    <span>
                        <input type="text" id="updchsngeAmount" name="updchsngeAmount" onpaste="clearNoNum(this)" onkeyup="clearNoNum(this)" class="specialSign,validate[required,custom[number],min[0],max[999999999]]"/>
                    </span>
            </p>
        </li>