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.
npm install swarm-js
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");
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);
})
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());
});
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);
});
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());
}
});
swarm.download("DAPP_HASH", "/target/dir")
.then(path => console.log(`Downloaded DApp to ${path}.`))
.catch(console.log);
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);
swarm.upload({pick: "file"}) // could also be "directory" or "data"
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.
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. For that, you just need to write a small config JSON with some info:
const Swarm = require("swarm-js");
// To run Swarm locally, you need a running Geth
// node and an Ethereum account/password
const config = {
// Either an address visible by `geth account list`, or the path to a private
// key (a file with 64 hex characteres); obviously, use an account without eth!
account: "d849168d52ea5c40de1b0b973cfd96873c961963",
// Password to unlock the address above; omit if you used a path to a key
password: "sap",
// Path where swarm-js will save its files
dataDir: process.env.HOME + "/Library/Ethereum/swarm-js",
// Path where geth.ipc is (that file is created when you start geth)
ethApi: process.env.HOME + "/Library/Ethereum/geth.ipc",
// Path where the swarm binary is (if there is nothing on this path, swarm-js
// will safely download and place it there). Add `.exe` to the end if you're
// on windows (otherwise it won't recognize as an executable file - eventually
// this will be improved)
binPath: process.env.HOME + "/Library/Ethereum/swarm-js/bin/swarm"
};
// Magically starts a local Swarm node
// Downloads binaries if necessary
Swarm.local(config, swarm => new Promise((resolve, reject) => {
// you can use the `swarm` object inside here
// 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!"));
If you have any trouble with this, please open an issue to let me know. 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.
TODO: document the API.
FAQs
Swarm tools for JavaScript.
The npm package swarm-js receives a total of 202,890 weekly downloads. As such, swarm-js popularity was classified as popular.
We found that swarm-js demonstrated a not healthy version release cadence and project activity because the last version was released a year ago. It has 2 open source maintainers collaborating on the project.
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