Walk a graph from leaf to root and build results based on a child/parent relationship

walk_graph.js

tree = {
  a: ['b', 'c', 'd'],
  b: ['e', 'f'],
  c: ['g', 'h'],
  h: ['i', 'j', 'k'],
  k: ['l'],
  l: ['m', 'n']
}

var _ = require('underscore');


function walk(node, tree, result) {
  if (tree[node] && tree[node].length > 0){
    _.each(tree[node], function(p) {
      var branch = walk(p, tree, []);
      _.each(branch, function(b) {
        result.push([node].concat(b));
      });
    });
    return result;
  } else {
    return node;
  }
}

var result = walk('a', tree, []);
result = _.map(result, function(r) {
  return r.join(' => ');
});

console.log(result);