ATLANTIC CITY, N.J. — For the first time, people in New Jersey will be able to click a mouse or swipe a screen to gamble online.

A five-day trial period of Internet gambling begins at 6 p.m. Thursday when players invited by casinos to test their systems make real-money bets online.

The test period is designed to see whether sophisticated technology designed to ensure that all gamblers are within New Jersey and that they are 21 or older works correctly. The test is also designed to evaluate electronic payment technology, and the integrity and functionality of the casino games themselves.

If all goes well, Internet gambling will be available to anyone within New Jersey starting Tuesday. The only other states to offer online gambling are Nevada and Delaware.

Online betting will mark the biggest expansion of gambling in New Jersey since casino gambling began in 1978.

“This is a very exciting time for Atlantic City and for the gaming industry,” said Alisa Cooper, a commissioner with the New Jersey Casino Control Commission. “I was born and raised here in Atlantic City, and I remember all of the excitement that filled this city 35 years ago when the first casino opened. There have been a lot of challenges and a lot of changes since those early days. With the dawn of Internet gaming, we are on the cusp of perhaps the biggest change — and challenge — since the first casino opened here.”

Hours before the test was to begin, one lawmaker was to unveil a proposal to expand Internet gambling in New Jersey. State Sen. Raymond Lesniak, who sponsored the law that authorized online betting, was to unveil his proposal at a news conference Thursday morning.

Then, at noon, the state was to release a list of gambling web sites that had passed rigorous testing and would be permitted to go live at 6 p.m. for the test.

Regulators say anywhere from 500 to several thousand people could be online at any one time during the test period. David Rebuck, director of the state Division of Gaming Enforcement, said he hopes to push the system and test its capacity.

He said all indications thus far are that the system should work as designed to meet strict regulation and protect players.

“I’m cautiously optimistic,” he said. “Testing has been going on for months, I don’t’ think there is any online gaming anywhere in the world that is going to be monitored as closely and protect the integrity of the games and players’ money as well these will.”