Mother always said it’s not nice to laugh while others cry, but there are exceptions. One is on display now in New York.

“It’s New ‘Work’ City! Rec­ord Low Jobless,” read the headline on Page 2 of Tuesday’s Post. The news is extremely good for workers, families and businesses — and very bad for the deep blue political class.

There are more than 4 millions jobs in the five boroughs, and the unemployment rate stands at a measly 4.2 percent — both are records, according to the quarterly report from Comptroller Scott Stringer. He found that, from April through June, 13,800 net new jobs were added, with 6,000 of them in high-wage sectors like securities that have average annual salaries of $220,000. Another encouraging sign: Government jobs fell by 1,000.

Lest the carpers carp about the rich getting richer, the report notes that every borough achieved a new low unemployment rate. They range from 3.4 percent in Queens to 5.3 percent in the Bronx.

Republican tax cuts in Washington for both businesses and families, along with reductions in regulations, are the clear causes. The nation’s GDP grew by a whopping 4.1 percent, though the city trailed that, growing by a still-respectable 2.7 percent.

The growth explosion contradicts the major messages of Democrats and their socialist fellow travelers, which increasingly covers most of the political class in the city and state. From the top to the bottom of the ballot, many candidates are running against President Trump, saying their fellow New Yorker is bad for New York.

Gov. Andrew Cuomo, for example, is airing television ads attacking Trump while publicly ignoring his primary opponent, Cynthia Nixon, who is pushing him further and further to the left. Cuomo has called the GOP tax cuts a “missile” and a “dagger” aimed at the heart of the state. The state is also suing to overturn the law as unconstitutional.

Those are especially odd claims given that more than 80 percent of state taxpayers got a tax cut under the law, according to nonpartisan estimates. For the one in five who will pay the same taxes or more, the chief reason is that they can now deduct only $10,000 of their exorbitant state and local taxes.

If Cuomo and others had reacted to the federal tax law as they should have — by cutting New York taxes — 100 percent of state residents would be paying less.

But too many pols measure success by how much money government spends, not by how much of their own money working families get to keep. And by defying the national trend, Cuomo, Mayor Bill de Blasio and city and state lawmakers are putting New York at a competitive disadvantage.

The outflow of high earners to Florida and other low-tax states is said to be accelerating, while New York remains a magnet for the poor because of its extra-generous social services. Free shelter on demand is the most glaring example of the come-and-get-it mentality.

At some point, the imbalance will put city and state finances at risk. And despite already-record government spending here, vital services such as mass transit have been shortchanged and mismanaged.

While most people want jobs and the freedom to pursue their own dreams, too many New York pols are falling sway to the socialist sermons that promise endless free stuff provided by an ever larger and more powerful government.

Indeed, the stunning primary victory of socialist Alexandria Ocasio-Cortez in a Queens House race has emboldened Nixon and others to claim that they own the future of the party. But while their support for single-payer health care, higher taxes and abolishing the federal Immigration and Customs Enforcement (ICE) agency is getting lots of attention, there is little sign that those are winning positions in city or statewide races even in New York.

Yet there is no question that Nixon, a de Blasio stalking horse, has Cuomo running scared.

His reaction has been to blow out the state budget and attack Trump relentlessly, apparently under the assumption that daily exhibition of his hatred for the president is the best way to appease unhappy voters and win a third term.

Maybe he’s right, but sometimes good politics is bad policy, and this is one of those times.

The federal tax cuts that Trump promised and delivered are yielding the jobs boom and wage growth in New York and across the country. Higher family incomes mean a better quality of life and more spending for millions of people, which in turn creates more new jobs and opportunities for millions of others.

That’s the economic circle of virtue that Democrats oppose and promise to repeal. Talk about being on the wrong side of history.

Hollers and cents: Lefties go fund ‘lying’ FBI duo

The only thing surprising about the FBI’s firing of Peter Strzok is that so many Americans think it is unwarranted.

Consider that Strzok raised over $300,000 for his legal claims on a GoFundMe page — in one day!

Strzok’s celebrity status is all the more staggering when you realize that his support is strongest on the political left. The people who, as a group, generally distrust trust law enforcement are ready to embrace a former FBI agent who displayed blatant bias toward the people he was investigating.

One of Strzok’s former bosses, Andrew McCabe, also was fired after being charged with lying to federal investigators. Yet his GoFundMe page raised $554,000 in just five days.

Of course, as with so much else on the left these days, all is forgiven if you hate Donald Trump. And bias is the least of what is acceptable. Talk of political assassination and threats of violence are no longer taboo — if they are aimed at Trump and his supporters.

This can’t end well.

Prez staff infection

Some years ago, former NYPD Commissioner Ray Kelly was talking about the strenuous effort the department put into its vetting of people who wanted to be cops. He explained that effort by saying simply, “We try not to hire our problems.”

Imagine if President Trump had followed that approach. Instead, from Paul Manafort to Michael Cohen and now Omarosa Manigault Newman, Trump has hired some of his biggest problems.

Those three people also are turning out to be Trump’s biggest gifts to the media he loves to hate. And he has no one to blame but the man in the mirror.

Art fund & games

Reader Ruth Cohen, MD, makes a wry appeal. She writes: “The front page of The New York Times highlights Views of Strong Women at an art fair in Seattle.

“I suggest Views of Weak Women at another art fair, perhaps in New York. For the sake of diversity, we should celebrate females each of whom is helpless in her own way.”

She adds: “I need funding and a venue.”