js verification example of legality and validity of IP and subnet mask_javascript skills

function checkIP(ip)
{
obj=ip ;
var exp=/^(d{1,2}|1dd|2[0-4]d|25[0-5]).(d{1,2}|1dd|2[0-4 ]d|25[0-5]).(d{1,2}|1dd|2[0-4]d|25[0-5]).(d{1,2}|1dd|2[0 -4]d|25[0-5])$/;
var reg = obj.match(exp);
if(reg==null)
{
return false;// Illegal
}
else
{
return true; //Legal
}
}

function checkMask(mask)
{
obj =mask;
var exp=/^(254|252|248|240|224|192|128|0).0.0.0|255.(254|252|248|240|224|192|128| 0).0.0|255.255.(254|252|248|240|224|192|128|0).0|255.255.255.(254|252|248|240|224|192|128|0)$/ ;
var reg = obj.match(exp);
if(reg==null)
{
return false; //"illegal"
}
else
{
return true; //"Legal"
}
}