Example 1: Here, const _ = require(‘lodash’) is used to import the lodash library in the file. Tree traversal library written in Underscore/Lodash fashion Here's a solution that flattens the elements and then filters the result to get the required elements before summing the val property:. filterState – the object which accumulates state for all filters we will change. Expand/ Collapse all control; Required Dependencies. Expand/ Collapse all control; Required Dependencies. Last active May 22, 2020. It returns a tree-like array of comments with nested replies and sub-replies and.. you know, some more replies inside. Lets say we have collection of objects: var a = [ {id: 10}, {id: 20}, {id: 30}, {id: 30}, {id: 20} ]; And if we need to get array with duplicate values of ids from array, one of the ways that we co… ES6 function to convert an Array of nodes (related by parent ID) - to a Tree structure: /** * Convert nodes list related by parent ID - to tree. An Easy Way to Build a Tree in JavaScript Using Object References , Building a tree structure in JavaScript can be easy if you think in terms While it's not completely necessary, let's start by creating a mapping of  Tree View Step 1) Add HTML: Example