This might work for you. Check out this incident record in the Demo09 instance:
https://demo09.service-now.com/nav_to.do?uri=incident.do?sys_id=a07f5030f14210007a18e0f8bdde3990.
I created a read-only, calculated URL field on the Incident form that grabs the URL out of the Short description field and will only appear if populated:
https://demo09.service-now.com/nav_to.do?uri=sys_dictionary.do?sys_id=9c7f5030f14210007a18e0f8bdde394f
Here is the calculation in the Dictionary record for the field:
answer='';
var linkAt = current.short_description.toLowerCase().indexOf('url: /http://')
if (linkAt >= 0) {
var linkTo = current.short_description.indexOf(' at ');
answer = current.short_description.substring(linkAt+5, linkTo);
}
You'll want to remove the leading "/" in "/http:" as without out, the post is all messed up.
There is also a UI Policy to display the field only if it is populated with something:
https://demo09.service-now.com/nav_to.do?uri=sys_ui_policy.do?sys_id=97806070f14210007a18e0f8bdde39f7
An alternative would be to create a UI Action that would parse the Short description field and open a new window/tab with the URL. Only display it based on the contents of the Short description field.
