Clarification on Timing area

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joe g

Feb 11, 2019, 10:09:27 AM2/11/19
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I am a bit confused as to the data that is displayed in the Timing area of Dev tools under the Performance tab. As I understand it, this area displays any W3C User timing marks, which seems to work well. However, in running a performance test for the test AngularJS page -, I discovered the following references listed there: 


  • Zone Aware Promise 
  • Zone: to string 
  • Zone: timers 
  • Zone: Blocking 
  • Zone: Event Target 
  • Zone: on property 
  • Zone: custom elements
  •  Zone: Canvas 
  • Zone: XHR 
  • Zone: Location
  • Zone: Promise Rejection Event

In looking over the code I don't see the typical coding references to add such a mark - e.g. window.performance && performance.mark && performance.mark("ATFAreaBegin") See

So I am curious as to:

  1. Why are these timings  listed in this section? Is the Timing section showing other types of timing events beyond the W3C user timing? I had assumed that only W3C timing marks would appear in this section These timings appear to be standard out of box in AngularJS since I didnt add anything to the code..
  2. Is anyone aware of documentation on the purpose of these and how they relate to web performance.
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