[removed] Find all parents for element in tree

Question

I have the objects tree, and i can\'t found all parents for concrete object id. Imagine i need to add some new field to each parent for object with id = 5. Can someone help

Answer 1

The easiest solution is to flatten the tree structure down so you can just look up ids and do a simple while loop

var tree = {
  id: 1,
  children: [
  	{
		id: 3,
		parentId: 1,
		children: [
		  	{
				id: 5,
				parentId: 3,
				children: []
			}
		]
	}
  ]
}

// We will flatten it down to an object that just holds the id with the object
var lookup = {}
function mapIt (node) {
  lookup[node.id] = node;
  //recursive on all the children
  node.children && node.children.forEach(mapIt);
}
mapIt(tree)

// This takes a node and loops over the lookup hash to get all of the ancestors
function findAncestors (nodeId) {
   var ancestors = []
   var parentId = lookup[nodeId] && lookup[nodeId].parentId
   while(parentId !== undefined) {
     ancestors.unshift(parentId)
     parentId = lookup[parentId] && lookup[parentId].parentId
   }
   return ancestors;
}

// Let us see if it works
console.log("5: ",  findAncestors(5))