swarm-js/examples/uploader_dapp/index.js

Swarm tools for JavaScript.

let swarm = Swarm.at("http://swarm-gateways.net");

// Uploads a file or directory to the Swarm network
const upload = dir => {
  swarm.upload(dir).then(print).catch(console.log);
};

// Downloads from Swarm and inserts on site
const download = () => {
  const hash = prompt("Hash:");
  if (hash) swarm.download(hash).then(print).catch(console.log);
};

// Sets the Swarm provider / gateway
const setProvider = e => {
  swarm = Swarm.at(document.getElementById("provider").value);
};

// Pretty printers
const print = val => {
  let p = document.createElement("p");
  let o = document.getElementById("output");
  p.appendChild(toHTML(val));
  o.insertBefore(p, o.firstChild);
};

// Interprets data as text/png/jpg/raw/directory, builds an HTML
const toHTML = val => {
  // Directory
  if (val instanceof Object && !val.length) {
    let table = document.createElement("table");
    for (var key in val) {
      let row = document.createElement("tr");
      let cell0 = document.createElement("td");
      let cell1 = document.createElement("td");
      cell0.appendChild(toHTML(key));
      cell1.appendChild(toHTML(val[key].data));
      row.appendChild(cell0);
      row.appendChild(cell1);
      table.appendChild(row);
    }
    return table;

  // String
  } else if (typeof val === "string") {
    let span = document.createElement("span");
    span.innerHTML = val;
    return span;

  // Buffer
  } else if (val.length) {
    // PNG
    if (val[1] === 80 && val[2] === 78 && val[3] === 71) {
      let image = document.createElement("img");
      image.src = "data:image/png;base64," + btoa(String.fromCharCode.apply(null,val));
      return image;

    // JPG
    } else if (val[0] === 0xFF && val[1] === 0xD8 && val[val.length-2] === 0xFF && val[val.length-1] === 0xD9) {
      let image = document.createElement("img");
      image.src = "data:image/jpg;base64," + btoa(String.fromCharCode.apply(null,val));
      return image;

    // Plain text / binary data
    } else {
      let isText = true;
      for (let i = 0; i < val.length; ++i)
        if (val[i] < 32 || val[i] > 126)
          isText = false;
      return toHTML(isText
        ? [].map.call(val, c => String.fromCharCode(c)).join("")
        : [].map.call(val, b => ("00"+b.toString(16)).slice(-2)).join(""));
    };
  };
};