Vibration API

W3C Candidate Recommendation

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Anssi Kostiainen, Intel


This specification defines an API that provides access to the vibration mechanism of the hosting device. Vibration is a form of tactile feedback.

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/.

The following changes (disposition of comments, redline) have been made since the W3C Last Call Working Draft 23 May 2013:

Before this specification exits Candidate Recommendation, two or more independent deployed implementations must demonstrate interoperability of each feature. No features have been marked as 'at risk'. The group will create an Implementation Report.

This document represents the consensus of the group on the scope and features of the Vibration API. It should be noted that the group is aware of more advanced use cases that cannot be realized using this simpler first version. The intent is to address them in a future revision.

This document was published by the Device APIs 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 to public-device-apis@w3.org (subscribe, archives). 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 18 September 2013. All comments are welcome.

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 the 5 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 contains Essential Claim(s) must disclose the information in accordance with section 6 of the W3C Patent Policy.

Table of Contents

1. Introduction

This section is non-normative.

The API is specifically designed to address use cases that require simple tactile feedback only. Use cases requiring more fine-grained control are out of scope for this specification. This API is not meant to be used as a generic notification mechanism. Such use cases may be handled using the Web Notifications [notifications] specification. In addition, determining whether vibration is enabled is out of scope for this specification.

2. Conformance

As well as sections marked as non-normative, all authoring guidelines, diagrams, examples, and notes in this specification are non-normative. Everything else in this specification is normative.

The key words MUST, MUST NOT, REQUIRED, SHOULD, SHOULD NOT, RECOMMENDED, MAY, and OPTIONAL in this specification are to be interpreted as described in [RFC2119].

This specification defines conformance criteria that apply to a single product: the user agent that implements the interfaces that it contains.

Implementations that use ECMAScript to implement the APIs defined in this specification must implement them in a manner consistent with the ECMAScript Bindings defined in the Web IDL specification [WEBIDL], as this specification uses that specification and terminology.

3. Terminology

The concepts browsing context and spin the event loop are defined in [HTML5].

4. Vibration Interface

partial interface Navigator {
    boolean vibrate ((unsigned long or sequence<unsigned long>) pattern);

The vibrate() method, when invoked, MUST run the algorithm for processing vibration patterns.

The rules for processing vibration patterns are as given in the following algorithm:

  1. Let pattern be the value of the first argument.
  2. If pattern is a list, proceed to the next step. Otherwise run the following substeps:
    1. Let list be an initially empty list, and add pattern to list.
    2. Set pattern to list.
  3. If the length of pattern exceeds an implementation-dependent limit, then return false and terminate these steps.
  4. If the length of pattern is even and is not zero, then remove the last entry in pattern.
  5. If any entry of pattern exceeds an implementation-dependent limit, then return false and terminate these steps.
  6. If the hidden attribute [PAGE-VISIBILITY] is set to true, then return false and terminate these steps.
    A trusted (also known as privileged) application that integrates closely with the operating system's functionality may vibrate the device even if such an application is not visible at all, and thus may ignore the previous step.
  7. An implementation MAY return false and terminate these steps.
    For example, an implementation might abort the algorithm because the user has set a preference indicating that pages at a given origin should never be able to vibrate the device, or an implementation might cap the total amount of time a page may cause the device to vibrate and reject requests in excess of this limit.
  8. Cancel the pre-existing instance of the processing vibration patterns algorithm, if any.
  9. If pattern is an empty list, or if the device does not provide a vibration mechanism (or it is disabled), then return true and terminate these steps.
  10. Return true, and then continue running these steps asynchronously.
  11. For each time in pattern, run the following substeps:
    1. If the index of time is even (the first entry has index 0), vibrate the device for time milliseconds.
    2. Otherwise wait for time milliseconds.

When the visibilitychange event [PAGE-VISIBILITY] is dispatched at the Document in a browsing context, the user agent MUST cancel the pre-existing instance of the processing vibration patterns algorithm, if any.

5. Examples

This section is non-normative.

In the following example the device will vibrate for 1000 milliseconds (ms):

Example 1
// vibrate for 1000 ms

// or alternatively

In the following example the pattern will cause the device to vibrate for 50 ms, be still for 100 ms, and then vibrate for 150 ms:

Example 2
navigator.vibrate([50, 100, 150]);

The following example cancels any existing vibrations:

Example 3
// cancel any existing vibrations

// or alternatively

A. Acknowledgements

The group is deeply indebted to Justin Lebar, Mounir Lamouri, Jonas Sicking, and the Mozilla WebAPI team for their contributions, and for providing the WebVibrator prototype as an initial input.

B. References

B.1 Normative references

Robin Berjon et al. HTML5. 17 December 2012. W3C Candidate Recommendation. URL: http://www.w3.org/TR/html5/
Jatinder Mann; Arvind Jain. Page Visibility. 14 May 2013. W3C Recommendation. URL: http://www.w3.org/TR/page-visibility/
S. Bradner. Key words for use in RFCs to Indicate Requirement Levels. March 1997. Internet RFC 2119. URL: http://www.ietf.org/rfc/rfc2119.txt
Cameron McCormack. Web IDL. 19 April 2012. W3C Candidate Recommendation. URL: http://www.w3.org/TR/WebIDL/

B.2 Informative references

Anne van Kesteren; John Gregg. Web Notifications. 14 June 2012. W3C Working Draft. URL: http://www.w3.org/TR/notifications/