Resource Timing Level 1 (original) (raw)

Abstract

This specification defines an interface for web applications to access the complete timing information for resources in a document.

Status of This Document

This section describes the status of this document at the time of its publication. Other documents may supersede this document. A list of current W3C publications and the latest revision of this technical report can be found in the W3C technical reports index at http://www.w3.org/TR/.

Implementers are encouraged to look at the latest version of Resource Timing before implementing this Candidate Recommendation.

This specification uses DOMHighResTimeStamp and time origin from High Resolution Time Level 2 [HR-TIME-2]. These were also defined in High Resolution Time Level 1 but Level 2 provides more refined definitions.

This document was published by the Web Performance Working Group as a Candidate Recommendation. This document is intended to become a W3C Recommendation. If you wish to make comments regarding this document, please send them topublic-web-perf@w3.org (subscribe,archives) with [ResourceTiming] at the start of your email's subject.W3C publishes a Candidate Recommendation to indicate that the document is believed to be stable and to encourage implementation by the developer community. This Candidate Recommendation is expected to advance to Proposed Recommendation no earlier than 22 August 2016. All comments are welcome.

Please see the Working Group's implementation report.

Publication as a Candidate Recommendation does not imply endorsement by the W3C Membership. This is a draft document and may be updated, replaced or obsoleted by other documents at any time. It is inappropriate to cite this document as other than work in progress.

This document was produced by a group operating under the5 February 2004 W3C Patent Policy.W3C maintains a public list of any patent disclosures made in connection with the deliverables of the group; that page also includes instructions for disclosing a patent. An individual who has actual knowledge of a patent which the individual believes containsEssential Claim(s) must disclose the information in accordance withsection 6 of the W3C Patent Policy.

This document is governed by the 1 September 2015 W3C Process Document.

Table of Contents

• 1. Introduction
• 2. Conformance
• 3. Terminology
• 4. Resource Timing
  • 4.1 Introduction
  • 4.2 Resources Included in the PerformanceResourceTiming Interface
  • 4.3 The PerformanceResourceTiming Interface
  • 4.4 Extensions to the Performance Interface
  • 4.5 Cross-origin Resources
    * 4.5.1 Timing-Allow-Origin Response Header
• 5. Process
  • 5.1 Processing Model
  • 5.2 Monotonic Clock
• 6. Privacy and Security
• A. Acknowledgments
• B. References
  • B.1 Normative references
  • B.2 Informative references

1. Introduction

This section is non-normative.

User latency is an important quality benchmark for Web Applications. While JavaScript-based mechanisms can provide comprehensive instrumentation for user latency measurements within an application, in many cases, they are unable to provide a complete end-to-end latency picture. This document introduces the PerformanceResourceTiming interface to allow JavaScript mechanisms to collect complete timing information related to resources on a document. Navigation Timing 2 [NAVIGATION-TIMING-2] extends this specification to provide additional timing information associated with a navigation.

For example, the following JavaScript shows a simple attempt to measure the time it takes to fetch a resource:

Example 1