This is the location of the addon folder if you are using Blender 2.79

If an animation key doesn't explicity define the scale value, it is set to (1, 1, 1) instead of (0, 0, 0).

This assignment to 'FLOAT_32' is unnecessary as it is redefined here before this value is used.
=>
https://lgtm.com/projects/g/mrdoob/three.js/snapshot/109bbfaeab1a0768acf40151648acfdf37a1949f/files/utils/exporters/blender/addons/io_three/constants.py?sort=entity-kind&dir=ASC

- Export materials before meshes, so they can be applied to faces.
- Raise an error on faces with > 4 vertices instead of writing JSON
  which will fail to load.
- Correctly export transparency -- black in Maya means opaque.

The path for addons is different for 2.76, after searching my filesystem
this is the location I found for my addons directory

Fixed blender  not export the material's opacity

verified that exporter works with all four cases: static meshes using JSONLoader and ObjectLoader and skinned meshes using JSONLoader and ObjectLoader

Loader.js loadTexture method looks for 'repeat' or 'mirror' strings but Blender JSON exporter write them as 'RepeatWrapping' and 'MirrorerRepeatWrapping'.
Loader code:
     if ( wrap[ 0 ] === 'repeat' ) texture.wrapS = RepeatWrapping;
     if ( wrap[ 0 ] === 'mirror' ) texture.wrapS = MirroredRepeatWrapping;

     if ( wrap[ 1 ] === 'repeat' ) texture.wrapT = RepeatWrapping;
     if ( wrap[ 1 ] === 'mirror' ) texture.wrapT = MirroredRepeatWrapping;

Current blender json export output:
     "mapDiffuse":"window.png",
     "mapDiffuseWrap":["RepeatWrapping","RepeatWrapping"], //loaded texture use ClampToEdgeWrapping

After fix:
     "mapDiffuse":"window.png",
     "mapDiffuseWrap":["repeat","repeat"], //loaded texture use RepeatWrapping

This reverts commit 41aae6d4.

This made exporting scenes with light not work.