The EXT_disjoint_timer_query.queryCounterEXT() method of the WebGL API records the current time into the corresponding query object.
queryCounterEXT(query, target)queryA WebGLQuery object for which to record the current time.
targetA GLenum specifying the target of the time query. Must be ext.TIMESTAMP_EXT.
None (undefined).
const ext = gl.getExtension("EXT_disjoint_timer_query");
const startQuery = ext.createQueryEXT();
const endQuery = ext.createQueryEXT();
ext.queryCounterEXT(startQuery, ext.TIMESTAMP_EXT);
// …
ext.queryCounterEXT(endQuery, ext.TIMESTAMP_EXT);