js-gitの使い方 ref: http://qiita.com/DUxCA/items/7653b826339c82acd64d

file0.js

// This provides symbolic names for the octal modes used by git trees.
window.modes = require('./lib/modes');

// Create a repo by creating a plain object.
window.repo = {};

// This provides an in-memory storage backend that provides the following APIs:
// - saveAs(type, value) => hash
// - loadAs(type, hash) => hash
// - saveRaw(hash, binary) =>
// - loadRaw(hash) => binary
require('./mixins/mem-db')(repo);

// This adds a high-level API for creating multiple git objects by path.
// - createTree(entries) => hash
require('./mixins/create-tree')(repo);

// This provides extra methods for dealing with packfile streams.
// It depends on
// - unpack(packStream, opts) => hashes
// - pack(hashes, opts) => packStream
require('./mixins/pack-ops')(repo);

// This adds in walker algorithms for quickly walking history or a tree.
// - logWalk(ref|hash) => stream<commit>
// - treeWalk(hash) => stream<object>
require('./mixins/walkers')(repo);

// This combines parallel requests for the same resource for effeciency under load.
require('./mixins/read-combiner')(repo);

// This makes the object interface less strict.  See it's docs for details
require('./mixins/formats')(repo);

file1.html

<script src="bundle.js"></script>

file2.txt

$ browserify main.js -o bundle.js
$ open index.html

file3.js

// First we create a blob from a string.  The `formats` mixin allows us to
// use a string directly instead of having to pass in a binary buffer.
repo.saveAs("blob", "Hello World\n", function(err, blobHash){
  console.log(err, blobHash);

  // Now we create a tree that is a folder containing the blob as `greeting.txt`
  repo.saveAs("tree", {
    "greeting.txt": { mode: modes.file, hash: blobHash }
  }, function(err, treeHash){
    console.log(err, treeHash);

    // With that tree, we can create a commit.
    // Again the `formats` mixin allows us to omit details like committer, date,
    // and parents.  It assumes sane defaults for these.
    repo.saveAs("commit", {
      author: {
        name: "Tim Caswell",
        email: "tim@creationix.com"
      },
      tree: treeHash,
      message: "Test commit\n"
    }, function(err, commitHash){
      console.log(err, commitHash);
    });
  });
});

file4.js

repo.saveAs("blob", "Hello World\n", function(err, blobHash){
  console.dir(blobHash);
  repo.loadAs("blob", blobHash, function(err, byteArray){
    console.log(byteArray);// -> [72, 101, 108, 108, 111, 32, 87, 111, 114, 108, 100, 10]
  });
});