Early depth test in WebGL I understand that in OpenGL early depth test can be performed in the rasterizer (before running the fragment shader), but is it the same case for WebGL? If so, how is early depth test enabled in WebGL?
In my answer I relate to WebGL 2 / Opengl ES 3.0. 

As far as I know ARB_shader_image_load_store is not supported. But there is discard available for fragment shaders in WebGL 2! So what you can do is to


make a depth pass with a straight-forward fragment shader and 
then in a second pass test gl_FragCoord.z against the value of the depth texture.


It's up to you, if it's worth the additional texture lookup and rendering the scene twice.