グラフの連結成分（JavaScript版） ref: https://qiita.com/kkdd/items/fce83a4fc3081378bc23

connected_components.js

var graph = {"0": ["1", "2", "3"], "1": ["2"], "2": [], "3": ["4", "6"], "4": [], "5": ["7"], "6": [], "7": []};
//       0
//     / | \
//    1--2  3
//          | \
//          4  6
//    5--7

function connected_components(graph) {
  var seen = [], push = Array.prototype.push;
  function notVisited(n) {return seen.indexOf(n) === -1;}
  function traverse(n) {
    seen.push(n);
    var nodes = [n];
    graph[n].forEach(function(m){
      if (notVisited(m)) push.apply(nodes, traverse(m)); // recursive, depth-first
    });
    return nodes;
  }
  var components = [];
  for (var n in graph) {
    if (notVisited(n)) components.push(traverse(n));
  }
  return components;
}

var ccs = connected_components(graph);
for (var i = 0, len = ccs.length; i < len; i++) {print("[", ccs[i], "]");} 

file0.txt

$ js connected_components.js
[ 0,1,2,3,4,6 ]
[ 5,7 ]