Retiring President Biden hit the shops on Black Friday and surprised onlookers by picking up a copy of a book describing the establishment of Israel as “colonialism” that’s been met with Palestinian “resistance” — an acquisition its author bemoaned was “4 years too late.”

Biden, 82, left Nantucket Bookworks holding in full view of the press a copy of “The Hundred Years’ War on Palestine: A History of Settler Colonial Conquest and Resistance, 1917-2017” by Columbia University professor emeritus Rashid Khalidi.

The book argues that “the modern history of Palestine can best be understood in these terms: as a colonial war waged against the indigenous population, by a variety of parties, to force them to relinquish their homeland to another people against their will.”

Khalidi, who is of Palestinian and Lebanese descent, refers to President-elect Donald Trump’s first administration as a “mouthpiece” for Israel and accuses Israeli Prime Minister Benjamin Netanyahu of leading “the most extreme government” in his country’s history.

The Arab Studies academic also slams what he describes as slanted press coverage in favor of Israel.

“I do not speak to the Post (or the Times for that matter), so this is not for publication, but my reaction is that this is 4 years too late,” Khalidi told The Post, which did not offer or agree to any terms conditioning that response as off the record or on background.

It was not immediately clear if Biden purchased the book or if it was given to him while in the shop — after he and first son Hunter Biden, 54, dined with first daughter Ashley Biden and other family members at the nearby Brotherhood of Thieves restaurant ahead of the island’s annual Christmas tree-lighting ceremony.

Biden has repeatedly referred to himself as a Zionist, meaning a supporter of the movement that spurred Jewish immigration to the Holy Land, leading to the establishment of the state of Israel in 1948.

“You don’t have to be a Jew to be a Zionist. I’m a Zionist,” Biden told visiting Israeli President Isaac Herzog on Nov. 12 in the Oval Office.

Staunch supporters of the Jewish state in US, however, faulted Biden for pausing shipments of heavy 2,000-pound bombs to Israel earlier this year after criticizing the humanitarian toll of the war. Other US aid continued despite the withheld munitions.

The retiring commander in chief visited Israel in a show of support shortly after Hamas terrorists murdered about 1,200 people on Oct. 7, 2023, and had to scale back his public appearances afterward, as furious activists persistently heckled him as “Genocide Joe” for backing Israel’s invasion of the Gaza Strip.

Thousands of pro-Palestinian protesters descended on the White House last November chanting “F–k Joe Biden” and “Genocide Joe has gotta go” — with some even painting the moniker on the White House gates alongside red handprints.Biden has increasingly criticized Netanyahu in the past year over civilian casualties in Gaza and reportedly has used expletives to describe him behind closed doors.

Khalidi’s book knocks Trump for enacting a range of policies such as moving the US embassy to Jerusalem and recognizing Israel’s annexation of the Golan Heights from Syria. The work was published in early 2020 before Trump brokered diplomatic relationships between Israel and five Muslim countries.

“Trump’s people abandoned even the shabby old pretense at impartiality. With this plan, the United States ceased to be ‘Israel’s lawyer,’ becoming instead the mouthpiece of the most extreme government in Israel’s history,” wrote Khalidi.

The book prescribes “a path based on equality and justice” that ends “the oppression of one people by another.” It cites discriminatory Israeli policies against Palestinians, whom Khalidi notes are of both Muslim and Christian backgrounds.

“Settler-colonial confrontations with indigenous peoples have only ended in one of three ways: with the elimination of full subjugation of the native population, as in North America; with the defeat and expulsion of the colonizer, as in Algeria, which is extremely rare; or with the abandonment of colonial supremacy, in the context of compromise and reconciliation, as in South Africa, Zimbabwe, and Ireland,” he writes.

“If the elimination of the native population is not a likely outcome in Palestine, then what of dismantling the supremacy of the colonizer in order to make possible a true reconciliation? The advantage that Israel has enjoyed in continuing its project rests on the fact that the basically colonial nature of the encounter in Palestine has not been visible to most Americans and many Europeans.”

Khalidi writes that the “popular resistance” among Palestinians “can be expected to continue to mount.”

The author praises the First Intifada by Palestinians against Israel, which left more than 2,000 dead after nearly six years of riots and rock-throwing between 1987 and 1993, ending in the Oslo Accords that granted limited self-rule to occupied areas of the West Bank and Gaza.

“The First Intifada was an outstanding example of popular resistance against oppression and can be considered as being the first unmitigated victory for the Palestinians in the long colonial war that began in 1917,” the book says.

He has less positive words for the subsequent Second Intifada that’s better known for suicide bombings targeting Israeli civilians, which resulted in a notorious security fence segregating Palestinian enclaves, writing that “the Second Intifada constituted a major setback for the Palestinian national movement.”

The Nantucket outing came just three days after Biden announced a US-brokered cease-fire between Hezbollah and Israel, as his administration continues to seek the release of both American and Israeli hostages held by Hamas in order to end the war in Gaza.

White House spokespeople did not immediately respond to The Post’s request for comment.