This is an experimental technology
Because this technology's specification has not stabilized, check the compatibility table for usage in various browsers. Also note that the syntax and behavior of an experimental technology is subject to change in future versions of browsers as the specification changes.

The WebGL2RenderingContext.beginQuery() method of the WebGL 2 API starts an asynchronous query. The target parameter indicates which kind of query to begin.


void gl.beginQuery(target, query);


A GLenum specifying the target of the query. Possible values:
  • gl.ANY_SAMPLES_PASSED: Specifies an occlusion query: these queries detect whether an object is visible (whether the scoped drawing commands pass the depth test and if so, how many samples pass).
  • gl.ANY_SAMPLES_PASSED_CONSERVATIVE: Same as above above, but less accurate and faster version.
  • gl.TRANSFORM_FEEDBACK_PRIMITIVES_WRITTEN: Number of primitives that are written to transform feedback buffers.
A WebGLQuery object for which to start the querying.

Return value



var query = gl.createQuery();
gl.beginQuery(gl.ANY_SAMPLES_PASSED, query);

// ...


Specification Status Comment
WebGL 2.0
The definition of 'beginQuery' in that specification.
Editor's Draft Initial definition.
OpenGL ES 3.0
The definition of 'glBeginQuery' in that specification.
Standard Man page of the (similar) OpenGL API.

Browser compatibility

Feature Chrome Firefox (Gecko) Internet Explorer Opera Safari
Basic support No support [2] Nightly build [1] No support No support No support
Feature Android Chrome for Android Firefox Mobile (Gecko) IE Mobile Opera Mobile Safari Mobile
Basic support No support No support No support No support No support No support

[1] WebGL 2 is enabled by default in Firefox Nightly. To enable it in a release version of Firefox, set the preference webgl.enable-prototype-webgl2 to true in about:config.

[2] To use an experimental implementation of WebGL 2 in Chrome, you have to start Chrome with the runtime flag --enable-unsafe-es3-apis.

See also

Document Tags and Contributors

 Contributors to this page: fscholz
 Last updated by: fscholz,