epperson

var orders = [
    { orderId: 'I8001', customerId: '5142' },
    { orderId: 'I1006', customerId: '5142' },
    { orderId: 'I1009', customerId: '5142' },
    { orderId: 'I1001', customerId: '5145' },
    { orderId: 'I9999', customerId: '5146' }
],
    
result = orders.reduce(function (r, a) {
  r[a.customerId] = r[a.customerId] || [];

epperson

using CMS.DocumentEngine;

namespace Example.Linq
{
    public static class DocumentSearchEventArgsExtensions
    {
        public static void AddContent(this DocumentSearchEventArgs searchEventArgs, string content)
        {
            searchEventArgs.Content += $" {content}";
        }

epperson

using System.Collections.Generic;
using System.Linq;
using System.Text.RegularExpressions;

using CMS;
using CMS.DataEngine;
using CMS.DocumentEngine;

using Example.Linq;
using Example.Search;