Sharepoint 2013 get ID of a user

Question

Hi
I am looking to figure out a way to get the ID of a user, given their name, so that I can use it in a call to /_layouts/15/userdisp?ID=n where 'n' is the ID of the user to redirect the person who is viewing the page to another person's Profile page. 
I am using JavaScript. I will not know the url of the mysites site hence using this method rather than the one using the MySites method.  I am on a search results page not a person search results page.
I am using SharePoint 2013 SP1 April 2015 CU.
Thanks Nigel
Nigel Price NJPEnterprises

Answer 1

GetUserProfilePropertyFor method
Gets the specified user profile property for the specified user.
The GetUserProfilePropertiesFor method is not implemented in the REST API. To get all user profile properties, call the GetPropertiesFor method
and then get the user profile properties from the UserProfileProperties property of the returned PersonProperties object.
Endpoint
/getuserprofilepropertyfor(accountname=@v, propertyname='<property name>')?@v='<account
name>'
Parameters
accountname
Type: String
The account name of the user, encoded and passed as an alias in the query string, as shown in the request example. See Implementation
notes for other example formats.
propertyName
Type: String
The case-sensitive name of the property to get.
HTTP method
GET
Response
Type: String
The specified profile property for the specified user.
  Request example
JavaScript
$.ajax({
url: "http://<site url>/_api/sp.userprofiles.peoplemanager
/getuserprofilepropertyfor(accountame=@v, propertyname='PictureURL')
?@v='i%3A0%23.f%7Cmembership%7Cuser%domain.onmicrosoft.com'",
type: "GET",
headers: { "accept": "application/json;odata=verbose" },
success: successHandler,
error: errorHandler
});rreplace propertyname='PictureURL' with propertyname='AccountName')