png-2-base64.js

#!/usr/bin/env node

var fs = require("fs"),
    util = require("util");

var mime = require("mime");

function base64Image(src) {
    var data = fs.readFileSync(src).toString("base64");
    return util.format("data:%s;base64,%s", mime.lookup(src), data);
}

var srcString, htmlString;

fs.readdir('./', function(err, files) {
  files.filter(function(file) {
    return (file.substr(-4) == '.png');
    })
    .forEach(function(file) {
      srcString = base64Image('./' + file);
      htmlString = "<img src='" + srcString + "'/>\n"; 
      fs.appendFileSync('./index.html', htmlString, {encoding:"utf-8"}, function() {
      });

  });
});