walkable-tree.js

// flatten a tree of arbitrary depth and complexity

class WalkableTree {
  constructor(data) {
    this.data = data
  }

  *[Symbol.iterator]() {
    for (let value of this.data) {
      if (Array.isArray(value)) {
        yield* new WalkableTree(value)
      } else {
        yield value
      }
    }
  }
}

const tree = [1, [2, [3, 4, 5], 6], 7, [8, 9]]
const walkableTree = new WalkableTree(tree)
for (let leaf of walkableTree) {
  console.log(leaf)
}

// outputs:
// 1
// 2
// 3
// 4
// 5
// 6
// 7
// 8
// 9