Just drag and drop your .JS 3D files on the drop-zone1 and let the magic happen.2
File API & FileReader API possibly not supported by your browser.
You can still try, but little chance of success though.
For a recent project I had to export some rigged and animated models (including morph targets) from 3DS Max to the ThreeJS JSON (JS) format, using mrdoob’s 3DS Max ThreeJSExporter (more specific ThreeJSAnimationExporter v0.8).
One of the missing options in this export plugin, is the ability to export multiple animations (or animation tracks / clips) into one JS file. So you can export the models one by one and then combine the animations by copy-pasting the animation data from multiple files into one. Since this is a rather time-consuming and error-prone method, I created a (quick and dirty)3 script-file to take this work off my / your hands.
In the script I just treat the files as basic text files, so I don’t actually process the JSON code. The resulting file can be used with the ThreeJS JSONLoader (animatedMesh).
1 It’s all client-side, so no uploads here.
2 The script uses the file names to set the animation “name” in the combined file.
3 Yes, I really mean quick and dirty..