Several examples of regular expressions in javascript

//清除左边空格
function js_ltrim(deststr)
{
if(deststr==null)return "";
var pos=0;
var retStr=new String(deststr);
if (retStr.lenght==0) return retStr;
while (retStr.substring(pos,pos+1)==" ") pos++;
retStr=retStr.substring(pos);
return(retStr);
}
//清除右边空格
function js_rtrim(deststr)
{
if(deststr==null)return "";
var retStr=new String(deststr);
var pos=retStr.length;
if (pos==0) return retStr;
while (pos && retStr.substring(pos-1,pos)==" " ) pos--;
retStr=retStr.substring(0,pos);
return(retStr);
}
//清除左边和右边空格
function js_trim(deststr)
{
if(deststr==null)return "";
var retStr=new String(deststr);
var pos=retStr.length;
if (pos==0) return retStr;
retStr=js_ltrim(retStr);
retStr=js_rtrim(retStr);
return retStr;
}

String.prototype.trim = function()
{
return this.replace(/(^\s*)|(\s*$)/g, "");
}

function checkMobile1(form)
{
if (form.mobile.value > "")
{
var reg=/13[5,6,7,8,9]\d{8}/;
if ( form.mobile.value.match(reg)== null)
{
alert("请输入正确的移动手机号码！");
form.mobile.focus(); return false;
}
}
return true;
}

//obj:数据对象
//dispStr :失败提示内容显示字符串
function checkUrlValid( obj, dispStr)
{
if(obj == null)
{
alert("传入对象为空");
return false;
}
var str = obj.value;
var urlpatern0 = /^https?:\/\/.+$/i;
if(!urlpatern0.test(str))
{
alert(dispStr+"不合法：必须以'http:\/\/'或'https:\/\/'开头!");
obj.focus();
return false;
}
var urlpatern2= /^https?:\/\/(([a-zA-Z0-9_-])+(\.)?)*(:\d+)?.+$/i;
if(!urlpatern2.test(str))
{
alert(dispStr+"端口号必须为数字且应在1－65535之间!");
obj.focus();
return false;
}
var urlpatern1 =/^https?:\/\/(([a-zA-Z0-9_-])+(\.)?)*(:\d+)?(\/((\.)?(\?)?=?&?[a-zA-Z0-9_-](\?)?)*)*$/i;
if(!urlpatern1.test(str))
{
alert(dispStr+"不合法,请检查!");
obj.focus();
return false;
}
var s = "0";
var t =0;
var re = new RegExp(":\\d+","ig");
while((arr = re.exec(str))!=null)
{
s = str.substring(RegExp.index+1,RegExp.lastIndex);
if(s.substring(0,1)=="0")
{
alert(dispStr+"端口号不能以0开头!");
obj.focus();
return false;
}
t = parseInt(s);
if(t<1 || t >65535)
{
alert(dispStr+"端口号必须为数字且应在1－65535之间!");
obj.focus();
return false;
}
}
return true;
}