Online retail spending in the U.S. during the third quarter of 2012 came in at more than $41.9 billion, a new record for the three months leading into the e-holiday shopping bonanza and a positive sign of things to come.

U.S. retail e-commerce sales from July through September were up 15 percent year-over-year, according to data released by analytics firm comScore. The positive growth rate in the third quarter marks the twelfth consecutive quarter of year-over-year growth and the eighth consecutive quarter of double-digit growth, comScore said.

“The Q3 growth rate of 15 percent growth remained in line with the prior quarter and provided confirmation of the strength in the e-commerce sector,” comScore chairman Gian Fulgoni said in a statement. “There appears to be strong enough footing to support a very healthy online holiday shopping season.”

The quarter was a successful one thanks, in part, to at least 16 percent year-over-year growth in e-commerce spending in each of the following categories: digital content and subscriptions, consumer electronics, event tickets, apparel and accessories, and computer software.

In some bad news for offline retailers, however, comScore found that consumers are increasingly opting to preview products in stores and price-check via smartphone before buying online, a practice known as “showrooming.”

According to a comScore survey, 37 percent of U.S. consumers said they engaged in showrooming, which marks a 5 percent increase over the past two quarters. Both Best Buy and Target have taken proactive stances against losing sales to online competitors. During the holiday season, the big-box retailers will be matching rivals’ online prices.

E-commerce photo via Shutterstock