Create a hierarchical structure starting from a flatten array of nodes

flattenToHierarchy.js

(function() {
  'use strict';
  
    // original data source
    var source = [{
      "id": 105142,
      "text": "root level",
      "parent": null
    }, {
      "id": 105150,
      "text": "root level",
      "parent": null
    }, {
      "id": 105195,
      "text": "root level",
      "parent": null
    }, {
      "id": 105190,
      "text": "first level",
      "parent": 105195,
    }, {
      "id": 105193,
      "text": "root level",
      "parent": null
    }, {
      "id": 105795,
      "text": "first level",
      "parent": 105193
    }, {
      "id": 105197,
      "text": "second level",
      "parent": 105203
    }, {
      "id": 105203,
      "text": "first level",
      "parent": 105193
    }];
  
    
  
  _.remove(source,
      function lookForChildren(node, index, collection) {
        if (node.parent) {
          // look for parent
          var parent = _.find(collection, {id: node.parent});
          if (parent) {
            // init parent children field
            parent.children = parent.children || [];
            // add to parent
            parent.children.push(node);          
          }
          // remove it
          return true;
        }
      }
    );
    
    // print hierarchical collection
    console.log(source);
    
})();