y.js

const Node = require('./lib/node.js')
const gatherDepSet = require('./lib/gather-dep-set.js')

const tree = new Node({
  path: '/some/path/to/root',
  pkg: { name: 'root', version: '1.0.0', dependencies: { a: '1', e: '1.x' }},
  children: [
    { pkg: { name: 'a', version: '1.0.0', dependencies: { b: '1.x', c: '1.0.x' }}},
    { pkg: { name: 'b', version: '1.0.0', dependencies: { d: '1.0.0' }}},
    { pkg: { name: 'c', version: '1.0.0' }},
    { pkg: { name: 'd', version: '1.0.0' }},
    { pkg: { name: 'e', version: '1.0.0', dependencies: { d: '1.0', e: '1' }}},
  ],
})

const a = tree.children.get('a')
const aSet = gatherDepSet([a], edge => edge.to !== a)
console.error([...aSet].map(n => n.name)) // [ 'a', 'b', 'c' ]

for (const node of tree.inventory.values()) {
  console.error('NODE', node.package._id, node.path)
  for (const edge of node.edgesIn) {
    const self = edge.from === node ? ' (self)' : ''
    console.error('  EDGE IN ', `${edge.from.name} -> ${edge.type}(${edge.name}@${edge.spec})${self}`)
  }
  for (const edge of node.edgesOut.values()) {
    const self = edge.to === node ? ' (self)' : ''
    console.error('  EDGE OUT', `${edge.from.name} -> ${edge.type}(${edge.name}@${edge.spec})${self}`)
  }
}

[ 'a', 'b', 'c' ]
NODE root@1.0.0 /some/path/to/root
  EDGE OUT root -> prod(a@1)
  EDGE OUT root -> prod(e@1.x)
NODE a@1.0.0 /some/path/to/root/node_modules/a
  EDGE IN  root -> prod(a@1)
  EDGE OUT a -> prod(b@1.x)
  EDGE OUT a -> prod(c@1.0.x)
NODE b@1.0.0 /some/path/to/root/node_modules/b
  EDGE IN  a -> prod(b@1.x)
  EDGE OUT b -> prod(d@1.0.0)
NODE c@1.0.0 /some/path/to/root/node_modules/c
  EDGE IN  a -> prod(c@1.0.x)
NODE d@1.0.0 /some/path/to/root/node_modules/d
  EDGE IN  b -> prod(d@1.0.0)
  EDGE IN  e -> prod(d@1.0)
NODE e@1.0.0 /some/path/to/root/node_modules/e
  EDGE IN  e -> prod(e@1) (self)
  EDGE IN  root -> prod(e@1.x)
  EDGE OUT e -> prod(d@1.0)
  EDGE OUT e -> prod(e@1) (self)