use requestAnimationFrame and support start/stop.

js/pixl/public/trixl.html

		gl.vertexAttribPointer(program.vertexPosBuffer, 3, gl.FLOAT, false, 0, 0);
		var angle = {x: 0, y: 0, z: 0};
		setInterval(function() {
			program.transform = gl.getUniformLocation(program, 'transform');
		program.transform = gl.getUniformLocation(program, 'transform');
		trixl.redraw = function() {
			var transform = matrix.multiplyMany4x4(
				matrix.rotateX(angle.x / 5),
				matrix.rotateY(angle.y / 5),
				matrix.rotateZ(angle.z / 5),
				//matrix.identity(4), matrix.identity(4) /*
				matrix.translate(-0.5, -0.5, -0.0),
				matrix.scale(0.5, 0.5, 0.5),
				matrix.rotateZ(angle.z / 4),
				//matrix.rotateY(angle.y / 10),
				matrix.rotateX(angle.x / 4),
				//matrix.translate(-0.5, -0.5, 0),
				matrix.translate(-0.5, -0.5, -0.5),
				matrix.scale(0.5, 0.5, 0.5)
				//matrix.translate(-0.5, -0.5, -0.5),
				matrix.translate(-0.0, -0.0, -0.1)
				//matrix.perspective(Math.PI / 3, trixl.window.w / trixl.window.h, 0, 2000) //*/
			);
			gl.uniformMatrix4fv(program.transform, false, matrix.transpose(transform, [4, 4]));
			trixl.debug_pos(matrix.multiply([1,1,1,1], [1, 4], transform, [4, 4]));
			gl.uniformMatrix4fv(program.transform, false, transform);
			gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT);
			gl.drawArrays(gl.TRIANGLES, 0, 6 * 6);
			angle.x += Math.PI / 10;
			angle.y += Math.PI / 30;
			angle.z += Math.PI / 50;
		}, 50);
			angle.y += Math.PI / 10;
			angle.z += Math.PI / 10;
		}
		trixl.step = function() {
			trixl.redraw();
			trixl.step.reqId = requestAnimationFrame(trixl.step);
		}
		trixl.start = function() {
			trixl.step.reqId = requestAnimationFrame(trixl.step);
		}
		trixl.stop = function() {
			cancelAnimationFrame(trixl.step.reqId);
			trixl.step.reqId = null;
		}
		trixl.start();
	</script>
</body>
</html>