JsTree example with lazy loading and checked state cascading turned off

script.js

$(document).ready(function() {

  $('.jstree').jstree({
    core: {
      data: {
        url: function(node) {
          return node.id === '#' ?
            'categories.json' :
            `categories-${node.id}.json`;
        }
      }
    },
    plugins: ['checkbox'],
    checkbox: {
      three_state: false // disable cascading checked state to all children nodes
    }
  });

  var categories = [];

  $('.jstree').on('loaded.jstree', function() {

    $.ajax({
      url: 'product_categories.json',
      success: function(data) {

        var categoriesToOpen = data.reduce(function(prev, curr) {
          return prev.concat(curr.path.split('/'));
        }, []);

        categories = data.reduce(function(prev, curr) {
          return prev.concat(curr.category_id);
        }, []);

        var set = new Set(categoriesToOpen); 

        $('.jstree').jstree('load_node', [...set]);

      }
    });

  });

  $('.jstree').on('load_node.jstree', function(_node, _status) {
    $('.jstree').jstree('select_node', categories);
  });

  $('.get-selected').on('click', function() {
    console.log($('.jstree').jstree('get_selected'));
  });

});

Thanks for your help!