swarm-js: A JavaScript repository from JohnnySheffield

Swarm.js

This library allows you to interact with the Swarm network from JavaScript. It:

Communicates with the network through the HTTP API;
Can be used either with a local node or a gateway;
Solves manifests recursively;
Enables you to upload/download raw data and directores;
Enables you to upload/download from disk or from pure JS;
Works on the browser and on Node.js;
Can automatically download the Swarm binaries safely and administer the local node for you.

Installing

npm install swarm-js

Basic usage

The simplest use case for Swarm is uploading/downloading raw data and directories. First, load the lib:

// Loads the Swarm API pointing to the official gateway
const swarm = require("swarm-js").at("http://swarm-gateways.net");

Upload raw data

To upload raw data, just call swarm.upload(buffer). It returns a promise with the uploaded hash.

const file = "test file";
swarm.upload(new Buffer(file)).then(hash => {
  console.log("Uploaded file. Address:", hash);
})

Download raw data

To download raw data, just call swarm.download(hash). It returns a promise with the data buffer.

const fileHash = "a5c10851ef054c268a2438f10a21f6efe3dc3dcdcc2ea0e6a1a7a38bf8c91e23";
swarm.download(fileHash).then(buffer => {
  console.log("Downloaded file:", buffer.toString());
});

Upload a directory

To upload a directory, just call swarm.upload(directory), where directory is an object mapping paths to entries, those containing a mime-type and the data (a buffer).

const dir = {
  "/foo.txt": {type: "text/plain", data: new Buffer("sample file")},
  "/bar.txt": {type: "text/plain", data: new Buffer("another file")}
};
swarm.upload(dir).then(hash => {
  console.log("Uploaded directory. Address:", hash);
});

Download a directory

To dowwnload a directory, just call swarm.download(hash). Swarm.js will return a directory instead of a buffer by detecting the existence of a manifest on that hash.

const dirHash = "7e980476df218c05ecfcb0a2ca73597193a34c5a9d6da84d54e295ecd8e0c641";
swarm.download(dirHash).then(dir => {
  console.log("Downloaded directory:");
  for (let path in dir) {
    console.log("-", path, ":", dir[path].data.toString());
  }
});

Download a file/directory to disk (on Node.js)

swarm.download("DAPP_HASH", "/target/dir")
  .then(path => console.log(`Downloaded DApp to ${path}.`))
  .catch(console.log);

Upload raw data, a file or a directory from disk (on Node.js)

swarm.upload({
  path: "/path/to/thing",      // path to data / file / directory
  kind: "directory",           // could also be "file" or "data"
  defaultFile: "/index.html"}) // optional, and only for kind === "directory"
  .then(console.log)
  .catch(console.log);

Upload raw data, a file or a directory from disk (on Browser)

swarm.upload({pick: "file"}) // could also be "directory" or "data"

Uploading an Ethereum DApp

When it comes to decentralized applications (DApps), the Ethereum network is responsible for the back-end logic, while Swarm is responsible for hosting and serving the front-end code. Hosting a DApp on Swarm is as simple as creating a directory with some HTMLs and a default route (the "index.html"). This, too, can be done with Swarm.js either from disk, or with pure JavaScript. Here is a sneak peek:

const swarm = require("swarm-js").at("http://swarm-gateways.net");

const indexHtml =
`<html>
  <body>
    <h3><img src="ethereum_icon.png"/> Swarm.js example DApp</h3>
    <p><a href="foo/test_text_1.txt">Test #1</a></p>
    <p><a href="foo/test_text_2.txt">Test #2</a></p>
  </body>
</html>`;

(...)

const exampleDApp = {
  ""                     : {type: "text/html", data: indexHtml},
  "/index.html"          : {type: "text/html", data: indexHtml},
  "/ethereum_icon.png"   : {type: "image/png", data: ethereumIconPng},
  "/foo/test_text_1.txt" : {type: "text/plain", data: testText1},
  "/foo/test_text_2.txt" : {type: "text/plain", data: testText2}
}

swarm.upload(exampleDApp)
  .then(console.log)
  .catch(console.log);

When you run that script, it outputs a hash. You can then use that hash to access the uploaded DApp, by either using a Swarm-enabled browser such as Mist, or through a gateway. That demo DApp is live and can be accessed:

If your browser recognizes Swarm, click here.
If you are in a conventional browser, click here.

Running a local node

Rather than using a gateway, you might wish to run your own local node. For that, you can either download/install/run it yourself, and then use require("swarm-js").at("http://localhost:8500"), or let Swarm.js take care of it:

const Swarm = require("swarm-js");

// To run Swarm locally, you need a running Geth
// node and an Ethereum account/password
const config = {
  account: "d849168d52ea5c40de1b0b973cfd96873c961963",
  password: "sap",
  dataDir: process.env.HOME+"/Library/Ethereum/testnet",
  ethApi: process.env.HOME+"/Library/Ethereum/testnet/geth.ipc"
};

// Magically starts a local Swarm node
// Downloads binaries if necessary
Swarm.local(config, swarm => new Promise((resolve, reject) => {

  // Uploads data using the local node
  swarm.upload(new Buffer("test")).then(hash => {
    console.log("Uploaded data. Address:", hash);

    // Closes the Swarm process.
    resolve();
  });

})).then(() => console.log("Done!"));

That function does everything required to start a local Swarm node, including downloading binaries (if not available yet) and manging the process. It then gives you a swarm object pointing to the local node. If the Swarm process was started by Swarm.js, it will be closed when you call resolve(). While it is up, you're able to access it on your browser at http://localhost:8500.

API

TODO: document the API.

JohnnySheffield/swarm-js