title: How to get current authorized user inside a TFS work item tracking control in JavaScript?
body: <p>I've been looking around and I've found that there's some REST API request that loads security groups and current identity:</p>
  
  <pre><code>tfs/DefaultCollection/Test/_api/_identity/ReadIdentitiesPageJson?__v=5
  </code></pre>
  
  <p>For example, it's called when Team Foundation Server's alert settings page is opened. </p>
  
  <p>Now I can't figure out which client TFS object receives that API call resulting JSON, because I require that to get current identity GUID in order to create an alert using a custom work item tracking control.</p>
  
  <p>My question is which client object holds such values? </p>
  
  <p>Here's a sample JSON returned by the above HTTP request:</p>
  
  <pre><code>{
      "identities": [{
          "IdentityType": "group",
          "FriendlyDisplayName": "Build Administrators",
          "DisplayName": "[Test]\\Build Administrators",
          "SubHeader": "[Test]",
          "TeamFoundationId": "881e0467-b2c5-467c-b145-a2c5a0966463",
          "Errors": [],
          "Warnings": [],
          "IsWindowsGroup": false,
          "Description": "Members of this group can create, modify and delete build definitions and manage queued and completed builds.",
          "Scope": "Test",
          "MemberCountText": "0 members",
          "IsTeam": false,
          "IsProjectLevel": true
      }, {
          "IdentityType": "group",
          "FriendlyDisplayName": "Contributors",
          "DisplayName": "[Test]\\Contributors",
          "SubHeader": "[Test]",
          "TeamFoundationId": "9da39547-51c0-41a8-a1f5-88e3936f0736",
          "Errors": [],
          "Warnings": [],
          "IsWindowsGroup": false,
          "Description": "Members of this group can add, modify, and delete items within the team project.",
          "Scope": "Test",
          "MemberCountText": "0 members",
          "IsTeam": false,
          "IsProjectLevel": true
      }, {
          "IdentityType": "group",
          "FriendlyDisplayName": "Project Administrators",
          "DisplayName": "[Test]\\Project Administrators",
          "SubHeader": "[Test]",
          "TeamFoundationId": "f0611ae0-3048-4bee-bffe-91bf84921052",
          "Errors": [],
          "Warnings": [],
          "IsWindowsGroup": false,
          "Description": "Members of this group can perform all operations in the team project.",
          "Scope": "Test",
          "MemberCountText": "0 members",
          "IsTeam": false,
          "IsProjectLevel": true
      }, {
          "IdentityType": "group",
          "FriendlyDisplayName": "Project Valid Users",
          "DisplayName": "[Test]\\Project Valid Users",
          "SubHeader": "[Test]",
          "TeamFoundationId": "0a969c95-452c-43c2-84ae-b59be9be0d3e",
          "Errors": [],
          "Warnings": [],
          "IsWindowsGroup": false,
          "Description": "Members of this group have acess to the team project.",
          "Scope": "Test",
          "MemberCountText": "6 members",
          "IsTeam": false,
          "IsProjectLevel": true,
          "RestrictEditingMembership": true
      }, {
          "IdentityType": "group",
          "FriendlyDisplayName": "Readers",
          "DisplayName": "[Test]\\Readers",
          "SubHeader": "[Test]",
          "TeamFoundationId": "e61e08fa-ead6-46b1-87a6-a90610b70ba0",
          "Errors": [],
          "Warnings": [],
          "IsWindowsGroup": false,
          "Description": "Members of this group have access to the team project.",
          "Scope": "Test",
          "MemberCountText": "0 members",
          "IsTeam": false,
          "IsProjectLevel": true
      }, {
          "IdentityType": "team",
          "FriendlyDisplayName": "Test Team",
          "DisplayName": "[Test]\\Test Team",
          "SubHeader": "[Test]",
          "TeamFoundationId": "5985029c-5cc6-4f07-ad2f-c5bcf687804c",
          "Errors": [],
          "Warnings": [],
          "IsWindowsGroup": false,
          "Description": "The default project team.",
          "Scope": "Test",
          "MemberCountText": "0 members",
          "IsTeam": true,
          "IsProjectLevel": true
      }, {
          "IdentityType": "user",
          "FriendlyDisplayName": "mfidemraizer",
          "DisplayName": "mfidemraizer",
          "SubHeader": "win7vm-dev\\mfidemraizer",
          "TeamFoundationId": "a595782b-afac-46d0-a800-8245d13bb25b",
          "Errors": [],
          "Warnings": [],
          "Domain": "win7vm-dev",
          "AccountName": "mfidemraizer",
          "IsWindowsUser": true,
          "MailAddress": ""
      }],
      "hasMore": false,
      "totalIdentityCount": 7
  }
  </code></pre>
  
  <p><strong>I need the <code>"TeamFoundationId": "a595782b-afac-46d0-a800-8245d13bb25b"</code> value.</strong></p>