‘Tis the season to head to stores, skip the cashiers and buy online. Retailers overall were projected to have a strong kickoff to the 2018 holiday shopping season — the five-day period that began with Thanksgiving. But while many reported healthy sales, online sellers have reaped the biggest surges with sales hitting record numbers, experts said. A combination of factors contributed to the holiday shopping boom online, including more blended retail, such as shoppers browsing for merchandise in stores before making purchases online from their smartphones to avoid the long checkout lines and lugging large items home, said Marshal Cohen, a retail industry expert at the NPD Group, a market research firm based in Port Washington, N.Y. A record $6.22 billion was spent online nationally on Black Friday, a 23.6 percent increase from the same day last year, according to Adobe Analytics, a division of San Jose, Calif.-based software company Adobe Inc. Brick-and-mortar stores, meanwhile, saw heavy traffic but down from years past, retail experts said.