forestry

A lightweight javascript library for creating and manipulating trees.

Install

$ npm install forestry --save     #npm
$ bower install forestry --save   #bower

API

Forestry.TRAVERSAL_TYPES

An enum like object that gives consumers access to the traversal types that can be passed into the traverse, find, all and reduce functions available on each Node. Forestry.TRAVERSAL_TYPES.DFS_PRE - Depth First Pre-order.
Forestry.TRAVERSAL_TYPES.DFS_POST - Depth First Post-order.
Forestry.TRAVERSAL_TYPES.BFS - Breadth First.

Forestry.Node

Each node has 'public' parent, data and children properties.
node.parent - the parent node of this node (undefined if the node is the root of the tree).
node.data - the data passed into the constructor.
node.children - an array of nodes that are children of this node (empty if the node is a leaf on the tree).

Constructor

Create a node with the given data.

var node = new Forestry.Node(data);

isRoot()

Returns true if the node has no parent and false otherwise.

node.isRoot();

isLeaf()

Returns true if the node has no children and false otherwise.

node.isLeaf();

index()

Returns the placement of the node within parent's children.

node.index();

level()

Returns the level of the node within the tree

node.level();

addChild(Type: Any [, val2 [, val3 [, valX]]])

Adds the given Node/s (if the arguments are not of type Node each is first wrapped) as children. Arguments can be provided as an array or series of arguments.
Returns the added node.

node.addChild(new Forestry.Node('1'));
node.addChild('some data');
node.addChild([new Forestry.Node({}), 'data']);
node.addChild('some', 'data', new Forestry.Node(12345));

remove()

Remove's the node from tree and returns it.

node.remove();

getRoot()

Returns the root node of the tree the node exists in.

node.getRoot();

climb (Type: Function)

Starting from the current node it climbs to the root node passing each node encountered through the given Function.

node.climb(function (node) {

});

traverse (Type: Function, [Type Forestry.TRAVERSAL_TYPE|String])

Traverses the tree passing each node through the given Function.
Traversal can be halted at any point by returning null from the Function.
An optional second argument can be given to select a traversal type.
If none is given it defaults to depth first pre-order.
All traversal types are non-recursive.

node.traverse(function (node) {

});

find (Type: Function, [Type: Forestry.TRAVERSAL_TYPE|String])

Finds and returns the first node in the tree that the predicate Function returns true for.
Returns null if no nodes match the predicate.
As it utilises the traverse function an optional second argument can be passed to select traversal type.

node.find(function (node) {

});

all (Type: Function, [Type: Forestry.TRAVERSAL_TYPE|String])

Finds and returns an array of nodes in the tree that the predicate Function returns true for.
Returns an empty array if no nodes match the predicate.
As it utilises the traverse function an optional second argument can be passed to select traversal type.

node.all(function (node) {

});

map (Type: Function)

Replaces each node with the return value of the passed Function. Returns the new 'mapped' tree.
If the function returns a value of type Node already processed child nodes are added using addChild.
If an Object is returned a children property is added to the object which is then an array populated with already processed child nodes.
If a non-object is returned it is wrapped in an object under a data property and processed child nodes are added to a children property as above.

node.map(function (node) {

});

reduce (Type: Any, Type: Function, [Type: Forestry.TRAVERSAL_TYPE|String])

Applies a Function against an accumulator and each node. Returns the accumulated value.
As it utilises the traverse function an optional second argument can be passed to select traversal type.

node.reduce(initialValue, function (currentValue, node) {

});

clone([Type: Function])

Returns a clone of the tree.
While this makes a clone of the actual tree structure it doesn't clone the data initially used in the creation of the Node unless the data object has a 'clone' method of it's own or a Function is passed in to take care of this (this could be a bespoke function or from another library e.g. lo-dash's clone/cloneDeep fuctions).
If no data clone function is provided (either as an argument or on each data object) any change to a cloned tree will be local but any change to the data property of each node will be echoed across both the cloned and original trees.
In some cases this may not matter (you may only want to manipulate the tree structure itself).

node.clone();

Forestry.parse(Type: Object, [Type: String], [Type: String])

Parses a given object to a Tree of Node objects and returns the root Node of the new tree.
Array's or Object's (key-value maps) of child nodes will be accepted. If an Object is found it is coerced to an Array and the key for each value Object is placed under the property _key.
By default children are expected to reside under a children property however an optional second argument can be passed to change this. In the example below we tell it to look for child nodes under the property links.
All properties except children (or the second argument if one is passed) will be taken as the basis for the data of each node. However, an optional third argument can be passed to cherry pick a single property. In the example below we take only the name as the data for each node resulting in data: 'Joanne', by default it would have been an object i.e. data: {name: 'Joanne'}.

var obj = {
      name: 'Joanne',
      links: [{
        name: 'Jake'
      }, {
        name: 'Jason',
        links: [{
          name: 'Jennifer'
        }]
      }]
    },
    rootNode = Forestry.parse(obj, 'links', 'name');

Issues

If you have any issues using this library or if you would like to suggest tweaks or new functionality please don't hesitate to give me a shout.

Contribution

• Fork the repository.
• run npm install in the project root folder to make sure you have all the dependencies needed.
• run npm test which will run jshint on all .js files within the project and run the tests.

License

MIT © Iain McDonald