Binding TreeGrid to XML Documents

import 'bootstrap.css';
import '@mescius/wijmo.styles/wijmo.css';
import './styles.css';
import * as wjGrid from '@mescius/wijmo.grid';
//
document.readyState === 'complete' ? init() : window.onload = init;
//
function init() {
    //
    var theGrid = new wjGrid.FlexGrid('#theGrid', {
        autoGenerateColumns: false,
        columns: [
            { binding: 'name', header: 'Name', width: '3*' },
            { binding: 'id', header: 'ID', dataType: 'String', width: '*' },
            { binding: 'price', header: 'Unit Price', format: 'n2', dataType: 'Number', width: '*' },
        ],
        headersVisibility: 'Column',
        childItemsPath: 'products',
        treeIndent: 25,
        itemsSource: getProductsByCategory()
    });
    //
    // parse an XML document into an array
    function getProductsByCategory() {
        var items = [], parser = new DOMParser(), xml = getXml(), doc = parser.parseFromString(xml, 'application/xml');
        //
        // get categories
        var categories = doc.querySelectorAll('category');
        for (var c = 0; c < categories.length; c++) {
            var category = categories[c];
            items.push({
                id: parseInt(category.getAttribute('id')),
                name: category.getAttribute('name'),
                products: []
            });
            //
            // get products in this category
            var products = category.querySelectorAll('product');
            for (var p = 0; p < products.length; p++) {
                var product = products[p];
                items[items.length - 1].products.push({
                    id: parseInt(product.getAttribute('id')),
                    name: product.getAttribute('name'),
                    price: parseFloat(product.getAttribute('price'))
                });
            }
        }
        //
        // all done
        return items;
    }
    //
    // get the XML string used as a data source
    function getXml() {
        return '<categories>' +
            '<category id="0" name="Beverages">' +
            '<product id="1" name="Chai" price="18" />' +
            '<product id="2" name="Chang" price="19" />' +
            '<product id="24" name="Guarana Fantastica" price="4.5" />' +
            '<product id="34" name="Sasquatch Ale" price="14" />' +
            '</category>' +
            '<category id="1" name="Condiments">' +
            '<product id="3"	name="Aniseed Syrup" price="10" />' +
            '<product id="4"	name="Chef Anton\'s Cajun Seasoning" price="22" />' +
            '<product id="5"	name="Chef Anton\'s Gumbo Mix" price="21.35" />' +
            '<product id="6"	name="Grandma\'s Boysenberry Spread" price="25" />' +
            '<product id="8"	name="Northwoods Cranberry Sauce" price="40" />' +
            '<product id="15" name="	Genen Shouyu" price="15.5" />' +
            '</category>' +
            '<category id="2" name="Confections">' +
            '<product id="16" name="Pavlova" price="17.45" />' +
            '<product id="19" name="Teatime Chocolate Biscuits" price="9.2" />' +
            '<product id="20" name="Sir Rodney\'s Marmalade" price="81" />' +
            '<product id="21" name="Sir Rodney\'s Scones" price="10" />' +
            '<product id="25" name="NuNuCa Nuß-Nougat-Creme" price="14" />' +
            '<product id="26" name="Gumbär Gummibärchen" price="31.23" />' +
            '<product id="27" name="Schoggi Schokolade" price="43.9" />' +
            '</category>' +
            '<category id="3" name="Dairy Products">' +
            '<product id="11" name="Queso Cabrales" price="21" />' +
            '<product id="12" name="Queso Manchego La Pastora" price="38" />' +
            '<product id="31" name="Gorgonzola Telino" price="12.5" />' +
            '<product id="32" name="Mascarpone Fabioli" price="32" />' +
            '<product id="33" name="Geitost" price="2.5" />' +
            '<product id="59" name="Raclette Courdavault" price="55" />' +
            '<product id="60" name="Camembert Pierrot" price="34" />' +
            '<product id="69" name="Gudbrandsdalsost" price="36" />' +
            '</category>' +
            '<category id="4" name="Grains/Cereals">' +
            '<product id="22" name="Gustaf\'s Knäckebröd" price="21" />' +
            '<product id="23" name="Tunnbröd" price="9" />' +
            '<product id="42" name="Singaporean Hokkien Fried Mee" price="14" />' +
            '<product id="52" name="Filo Mix" price="7" />' +
            '<product id="56" name="Gnocchi di nonna Alice" price="38" />' +
            '<product id="57" name="Ravioli Angelo" price="19.5" />' +
            '<product id="64" name="Wimmers gute Semmelknödel" price="33.25" />' +
            '</category>' +
            '<category id="5" name="Meat/Poultry">' +
            '<product id="9" name="Mishi Kobe Niku" price="97" />' +
            '<product id="17" name="Alice Mutton" price="39" />' +
            '<product id="29" name="Thüringer Rostbratwurst" price="123.79" />' +
            '<product id="53" name="Perth Pasties" price="32.8" />' +
            '<product id="54" name="Tourtière" price="7.45" />' +
            '<product id="55" name="Pâté chinois" price="24" />' +
            '</category>' +
            '<category id="6" name="Produce">' +
            '<product id="7" name="Uncle Bob\'s Organic Dried Pears" price="30" />' +
            '<product id="14" name="Tofu" price="23.25" />' +
            '<product id="28" name="Rössle Sauerkraut" price="45.6" />' +
            '<product id="51" name="Manjimup Dried Apples" price="53" />' +
            '<product id="74" name="Longlife Tofu" price="10" />' +
            '</category>' +
            '<category id="7" name="Seafood">' +
            '<product id="10" name="Ikura" price="31" />' +
            '<product id="13" name="Konbu" price="6" />' +
            '<product id="18" name="Carnarvon Tigers" price="62.5" />' +
            '<product id="30" name="Nord-Ost Matjeshering" price="25.89" />' +
            '<product id="36" name="Inlagd Sill" price="19" />' +
            '<product id="37" name="Gravad lax" price="26" />' +
            '<product id="40" name="Boston Crab Meat" price="18.4" />' +
            '</category>' +
            '</categories>';
    }
}