How can I use OpenGL 4 features through WebGL

I want to use some of the features of OpenGL 4 (specifically, tessellation shaders and newer shader language versions) from WebGL. Is this possible, in either a standards-compliant or a hackish way? Is there some magic开发者_StackOverflow value I could use instead of, say, gl.FRAGMENT_SHADER to tell the underlying GL implementation to compile tessellation shaders?

WebGL is based on the OpenGL ES 2.0 Specification so you wouldn't be able to use GL4 unless the browser also somehow exposes a GL4 interface to JavaScript which i doubt. Even if a browser would give you such an interface it would only work on that browser.