Above the Fold (ATF) Rendering

ATF rendering gives the appearance of a website loading faster than it actually does. The goal is to render first all the parts of a page that are visible and then, before the user scrolls down, render the rest of the page that is not initially visible.

A slot can have an "above the fold" designation, which displays an icon on the tab.


above the fold icon on Slot tab

For a slot to be rendered in this new way, it must be marked with scs-atf, as follows:

<div class="scs-slot scs-atf" id="headline"></div>

A component needs to notify the renderer when it is done rendering. Out-of-the-box components do this by default. A custom component can make additional calls and needs to do the following:

  1. Notify the renderer that it wants the renderer to wait until it is completed rendering.
  2. Notify the renderer when it has completed.

For #1, against the custom component's appinfo.json file, add in the following property:

   "initialData": {
        . . .
        "customRenderComplete": true,
        . . .

For #2, in the component's render.js file, make sure that you let the renderer know when you're done by calling:

 SitesSDK.setProperty('renderComplete', true);

If not all components in an ATF slot report back that they are done in a timely manner, then the renderer will wait for 2 seconds before continuing with the rest of the page. If you know this will not be long enough, you can extend the time by declaring the following global variable in a page template:

var SCSAtfPassTimeout = 3000;

Note:

The time is in milliseconds so this example set the timeout to 3 seconds.

An API provides diagnostic data for the ATF process. You can call the following method in the debug console, or you can access it from a page if needed:

SCSRenderAPI.getRenderMetrics();

For example:

{currentTime: 16243.400000000001, renderStartTime: 264.36, atfPassEndTime: 306.535, mainPassStartTime: 316.475, mainPassEndTime: 331.38500000000005, …}

1.   atfComponentCount:13

2.   atfPassEndTime:306.535

3.   completionCount:23

4.   completionRecords:Array(23)

1.   0:{atf: true, componentId: "a7afdd33-3fbb-4329-bc1b-6be60056a995", time: 280.065}

2.   1:{atf: true, componentId: "edfcfcb4-b0d3-422f-aa59-5c925bbbebee", time: 283.54}

3.   2:{atf: true, componentId: "c1c3aec8-e52f-406c-8c29-ab69c05877ed", time: 283.56000000000006}

4.   3:{atf: true, componentId: "b3a31dc6-62a1-44d9-9c80-bdb2c5bedaaa", time: 284.13000000000005}

5.   4:{atf: true, componentId: "c05aa1a2-c11c-4ef5-9051-4799c5bee24a", time: 284.15500000000003}

6.   5:{atf: true, componentId: "bafd4047-06ec-4739-9b23-9db74f573f30", time: 294.665}

7.   6:{atf: true, componentId: "e7d49528-0357-4b45-801e-b3a2716a086c", time: 297.995}

8.   7:{atf: true, componentId: "a5f33674-4022-4138-8cc5-fef00c02a557", time: 299.78000000000003}

9.   8:{atf: true, componentId: "ccfedc98-1dbd-440e-b867-5e683cea2ec5", time: 301.19500000000005}

10. 9:{atf: true, componentId: "d691bc44-fed9-474a-9806-2191f46a5e2e", time: 302.46}

11. 10:{atf: true, componentId: "cf613054-05d8-40dd-83a0-718760d7bc73", time: 303.79}

12. 11:{atf: true, componentId: "b4a6ef98-ffc8-48c7-987c-63346ee97bcc", time: 305.115}

13. 12:{atf: true, componentId: "de1fa2ce-66ba-419b-b517-2cb4a7601c3b", time: 306.535}

14. 13:{atf: false, componentId: "ba3f8ed4-31d4-4347-b6f0-f1019783a57c", time: 318.665}

15. 14:{atf: false, componentId: "ae8af486-76b3-47cd-9989-db4212eefebb", time: 320.45500000000004}

16. 15:{atf: false, componentId: "a48b5abb-49b2-4456-90bd-a3de998150c8", time: 320.48}

17. 16:{atf: false, componentId: "a9650e6d-7e7e-42a2-b758-58f2aeab18a2", time: 322.61500000000007}

18. 17:{atf: false, componentId: "aca9836a-f955-4aa7-8db2-fd3cf1189dea", time: 324.23500000000007}

19. 18:{atf: false, componentId: "e3d7941c-fbc7-4da9-963b-e3810b6467d4", time: 325.85}

20. 19:{atf: false, componentId: "eecde809-da54-4066-9326-73f9d9c35fe4", time: 327.315}

21. 20:{atf: false, componentId: "e8f4fb16-4e15-4570-b7de-304e99e449a7", time: 328.74}

22. 21:{atf: false, componentId: "a7baa06e-7f30-42c7-94f4-e171ab2edcd6", time: 330.09000000000003}

23. 22:{atf: false, componentId: "fd603b96-2beb-4e87-a54f-12d0e264cd0a", time: 331.38500000000005}

24. length:23

25. __proto__:Array(0)

5.   componentCount:23

6.   currentTime:16243.400000000001

7.   mainPassEndTime:331.38500000000005

8.   mainPassStartTime:316.475

9.   renderStartTime:264.36

10. __proto__:Object