By Suzanne Kapner 

The Covid-19 pandemic didn't just change consumer habits. It also prompted retailers to rethink Black Friday, one of the biggest shopping days of the year.

Many stores stayed closed this Thanksgiving, in a break with a pre-pandemic tradition of opening Thursday evening. Retailers have moved away from door-busters, the deeply discounted items available for a limited time that drew hordes of shoppers to stores on Friday morning. Instead, they have been dangling Black Friday deals all month, both online and in stores. Some are hosting streaming events on their websites on Friday as an alternative to visiting a store.

"Customers are shopping differently this year," said Greg Revelle, Kohl's Corp.'s chief marketing officer. "We had to alter our Black Friday strategy," he said.

Stores are trying to balance what forecasters predict will be record holiday sales with supply-chain constraints that have kept some items in short supply.

Many consumers were able to save money during the pandemic and are now spending freely despite rising inflation. That bodes well for the holiday season, executives and analysts said.

The National Retail Federation expects sales during November and December to rise by a record 8.5% to 10.5% to as much as $859 billion, compared with a year ago. That is in contrast to an average increase of 4.4% over the past five years.

The trade group predicts that nearly 2 million more people, or a total of 158.3 million, will shop over Thanksgiving weekend this year, compared with last year. Still, that is down from the 165.3 million people who shopped over the same weekend in 2019, before the pandemic.

As vaccines become widely available and Covid-19-related restrictions are eased, people have been returning to concerts, the movies and traveling. For many, shopping in stores on Black Friday is a social ritual they are eager to resume.

"I used to go to the mall on Black Friday with my family or friends," said Caleb Reed, who lives in Boise, Idaho. "I missed being able to do that last year."

The 24-year-old said he plans to head to the mall this year. "A big part of Black Friday shopping in person is the experience of going store to store," he said. "When you're shopping online, it's just about getting the best deal."

Concerns about out-of-stock items and potential shipping delays as well as Black Friday deals on offer since the beginning of November prompted consumers to shop earlier. Sixty-one percent of shoppers surveyed by the NRF said they had started their holiday shopping before Thanksgiving, up from 51% a decade ago. Digital out-of-stock messages are up 261% in November, compared with November 2019, according to Adobe Inc., a software company that tracks online shopping.

Andrew Diaz said he completed more than half of his holiday shopping before Thanksgiving. Worried about shipping delays, the 24-year-old said he plans to visit the mall near his Costa Mesa, Calif., home on Friday to purchase the rest of the items on his list. "I'm worried that if I wait, the stores will be out of stock," he said. "It doesn't seem like they have enough products."

While larger retailers such as Walmart Inc. and Target Corp. accelerated imports and chartered their own ships to sidestep supply-chain problems, some smaller chains, including Gap Inc., Victoria's Secret & Co. and Urban Outfitters Inc. are scrambling to keep their shelves stocked.

Delays caused by Covid-19 outbreaks that disrupted production in Asia and a surge of imports as retailers stocked for the holiday season have created a backlog of container ships waiting to enter Southern California ports. On Tuesday, Gap predicted supply-chain disruptions would result in about $550 million to $650 million in lost sales.

E-commerce sales surged last holiday season, while many nonessential retailers were either temporarily closed or had restricted capacity. This year, online sales for November and December are expected to total $207 billion, a 10% increase over 2020, according to Adobe. That is less than the 32% jump last year, compared with 2019. Some chains, including Best Buy Co. and Dick's Sporting Goods Inc., recently reported a slowdown in digital sales.

Visits to physical stores are picking up, but foot traffic is still below pre-pandemic levels. For the week ended Nov. 20, visits to physical stores were 12.4% below the same week in 2019, according to Sensormatic Solutions, which tracks footsteps with cameras placed at stores.

Brian Field, senior director of Sensormatic Solutions' retail consulting practice, said he expects traffic during this year's Black Friday week to fall from 2019 levels, but the drop won't be as steep as last year.

Retailers are giving shoppers less reason to visit stores this Black Friday compared with prior years. The term "door-buster" didn't appear in Black Friday advertisements this year at Walmart, Best Buy and other major retailers analyzed by online discount marketplace Brad's Deals.

Chains including Macy's Inc. and Saks Fifth Avenue are hosting gift-themed streaming events on their websites on Black Friday. Singer-songwriter Malia will host "The Best Black Friday Deals" airing at 4 p.m. ET on Macy's website. Saks's show will feature La Mer skin care products.

"People got comfortable communicating through digital platforms during Covid," said Emily Essner, Saks's chief marketing officer. "This is a customer behavior that has absolutely changed and is not going away."

Lana Hinds and her sister used to map out their Black Friday shopping plans on Thursday as soon as the turkey was cleared from the table. Then, they would get up early Friday morning to wait in line at big-box chains. This year, Ms. Hinds, who lives in Greenville, S.C., plans to do all her holiday shopping online.

"It's easier to shop from my home," the 35-year-old said. "I don't have to deal with the traffic, getting up early, or waiting in line."

Write to Suzanne Kapner at Suzanne.Kapner@wsj.com