js 输入框只能输入11位数字
文本框：
<input type="text" size="30" id="orderPersonTel" class="ma_input" maxlength="18" onkeyup="chekNum(this)"/>

//输入11位数字验证函数
    function chekNum(obj){
        obj.value = obj.value.replace(/[^\d.]/g,"");
        obj.value = obj.value.replace(/^\./g,"");
        obj.value = obj.value.replace(/\.{2,}/g,".");
        obj.value = obj.value.replace(".","$#$").replace(/\./g,"").replace("$#$",".");
        if(obj.value.length > 11){
                obj.value = obj.value.substring(0,11);     
        }
    }