A function to flatten a tree, depth-first. It's an implementation of this algorithm: http://cl.ly/image/1X1i0b1v1H2d Assumes the tree is built via nodes that have a property named 'children' which is an array of other nodes.

flattenTreeDepthFirst.js

function flattenTreeDepthFirst(rootNode) {
  var nodes = [rootNode];
  var childArraysQueue = [];

  if (rootNode.children) {
    childArraysQueue.push(rootNode.children);
  }

  while (childArraysQueue.length > 0) {
    var children = childArraysQueue[0];
    if (children.length > 0) {
      var child = children.shift();
      if (children.length < 1) {
        childArraysQueue.shift();
      }
      if (child.children && child.children.length > 0) {
        childArraysQueue.unshift(child.children);
      }
      nodes.push(child);
    }
  }

  return nodes;
}