<!DOCTYPE html>
<html lang="ja">
<head>
<meta charset="UTF-8">
<title></title>
</head>
<body>
<canvas id = "canvas">
</canvas>
<script>
var canvas = document.getElementById('canvas');
var gl = canvas.getContext('webgl') || canvas.getContext('experimental-webgl');
var extensions = gl.getSupportedExtensions();
for(var e in extensions){
document.write(extensions[e] + ",");
}
</script>
</body>
</html>
こんな感じで，gl.getSupportedExtensions()を呼び出せば，拡張機能の一覧が取得できる．
ANGLE_instanced_arrays,EXT_blend_minmax,EXT_clip_control,EXT_color_buffer_half_float,EXT_depth_clamp,EXT_float_blend,EXT_frag_depth,EXT_polygon_offset_clamp,EXT_shader_texture_lod,EXT_texture_compression_bptc,EXT_texture_compression_rgtc,EXT_texture_filter_anisotropic,EXT_texture_mirror_clamp_to_edge,EXT_sRGB,OES_element_index_uint,OES_fbo_render_mipmap,OES_standard_derivatives,OES_texture_float,OES_texture_float_linear,OES_texture_half_float,OES_texture_half_float_linear,OES_vertex_array_object,WEBGL_color_buffer_float,WEBGL_compressed_texture_astc,WEBGL_compressed_texture_etc,WEBGL_compressed_texture_etc1,WEBGL_compressed_texture_s3tc,WEBGL_compressed_texture_s3tc_srgb,WEBGL_debug_renderer_info,WEBGL_debug_shaders,WEBGL_depth_texture,WEBGL_draw_buffers,WEBGL_lose_context,WEBGL_multi_draw,WEBGL_polygon_mode