The WebGLRenderingContext.copyTexSubImage2D() method of the WebGL API copies pixels from the current WebGLFramebuffer into an existing 2D texture sub-image.
The WebGLRenderingContext.deleteTexture() method of the WebGL API deletes a given WebGLTexture object. This method has no effect if the texture has already been deleted.
The WebGLRenderingContext.compressedTexSubImage2D() method of the WebGL API specifies a two-dimensional sub-rectangle for a texture image in a compressed format.