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.clientWaitSync() method of the WebGL 2 API blocks and waits for a WebGLSync object to become signaled or a given timeout to be passed.


GLenum gl.clientWaitSync(sync, flags, timeout);


A WebGLSync object on which to wait on.
A GLbitfield specifying a bitwise combination of flags controlling the flushing behavior. May be gl.SYNC_FLUSH_COMMANDS_BIT.
A GLint64 specifying a timeout (in nanoseconds) for which to wait for the sync object to become signaled. Must not be larger than gl.MAX_CLIENT_WAIT_TIMEOUT_WEBGL.

Return value

A GLenum indicating the sync object's status.

  • gl.ALREADY_SIGNALED: Indicates that the sync object was signaled when this method was called.
  • gl.TIMEOUT_EXPIRED: Indicates that the timeout time passed and that the sync object did not become signaled.
  • gl.CONDITION_SATISFIED: Indicates that the sync object was signaled before the timeout expired.
  • gl.WAIT_FAILED: Indicates that an error occurred during the execution.


var sync = gl.fenceSync(gl.SYNC_GPU_COMMANDS_COMPLETE, 0);
var status = gl.clientWaitSync(sync, 0, 0);


Specification Status Comment
WebGL 2.0
The definition of 'clientWaitSync' in that specification.
Editor's Draft Initial definition for WebGL.
OpenGL ES 3.0
The definition of 'glClientWaitSync' 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,