There's no denying that online retailers continue to gain at the expense of bricks-and-mortar chains, and there will be plenty of investing opportunities in e-commerce in the year ahead. 

Let's look at five companies that should beat the market in 2014.

It may not seem fair to start with the obvious, but e-tail is really a field where the richest keeps getting richer. Industry tracker comScore reported last week that online sales this holiday shopping season -- via desktop -- climbed just 10% through Dec. 22. Mobile-based shopping is growing faster than that, but it's still impressive that analysts see Amazon's revenue climbing 22% for the holiday quarter that ended last week.

It wasn't a surprise to see Amazon hit a fresh all-time high last week. Amazon is in the right place at the right time, and its success with the Kindle, Kindle Fire, and Amazon Prime show that there's plenty that's proprietary and unique to set itself and its digital ecosystem apart from the competition.

2. Groupon (NASDAQ:GRPN) 
One of last year's biggest turnaround stories was Groupon. The same daily-deals leader that surrendered 76% of its value in 2012 made back a good chunk of that slide by soaring 142% in 2013.

At its darkest hour -- when bookings for its local deals were struggling -- Groupon embraced physical goods as an online retailer of clearance and closeout items. Groupon's flagship deals offering vouchers good for discounts on local eateries, spas, and other experiences have bounced back in this country, and Groupon's been able to parlay its thick Rolodex into becoming a provider of a growing number of merchant services.

3. Zulily (UNKNOWN:ZU.DL)
One of 2013's more intriguing IPOs was Zulily. The November debutante priced its shares at $22, soaring 71% on its first day of trading.

Zulily is a fast-growing provider of flash sales on fashionable apparel and accessories for kids and their mothers. It may seem like too specific a concentration to pan out, but Zulily's appeal makes it one of the faster-growing e-commerce players in the country.

Wall Street sees revenue soaring 67% in 2014, with profitability quadrupling to $0.20 a share.  

4. Vipshop Holdings (NYSE:VIPS) 
If you want an established e-commerce play that's growing even faster than Zulily you may have to travel to China. Vipshop has been a very profitable provider of fashion-oriented flash sales, and Wall Street's betting on earnings more than doubling to $2.13 a share this year on a 69% top-line surge.

There are risks with buying into China, of course. However, Vipshop has won over non-believes after more than quadrupling in value last year.

5. Liquidity Services (NASDAQ:LQDT)
Liquidity Services isn't growing as quickly as the other four companies on this list. The pros see revenue growth in fiscal 2014 clocking in nearly unchanged from last year. Operating a popular online marketplace for salvage goods isn't apparently as lucrative as it used to be, but don't turn your back on Liquidity Services.

The stock is too cheap at this point, fetching 14 times this year's projected profitability and a multiple of just 13 based on next year's forecast. The liquidator is on sale itself.