Tree-recursion.js

const categories = [
  {
    name: 'clothing',
    category: null
  },
  {
    name: 'adult',
    category: 'clothing'
  },
  {
    name: 'men',
    category: 'adult'
  },
  {
    name: 'jeans',
    category: 'men'
  },
  {
    name: 'jacket',
    category: 'jeans'
  },
  {
    name: 'dark blue',
    category: 'jacket'
  }
];

const createTree = (tree, parent = null) => {
  let subtree = {};
  tree.filter(x => x.category === parent)
    .forEach(x => subtree[x.name] = createTree(tree, x.name));
  return subtree;
};

createTree(categories);