Javascript的數學難題
首先先考大家幾個數學題，如果這幾題的答案你都能順利的回答，那恭喜你！你可以安心地閱讀這篇文章，你一定能看懂！
題目ㄧ. 0.1 + 0.2 = ？
題目二. 1 – 0.9 = ？
題目三. 0.69 x 10 = ？
相信上面三個簡單的十進位數學運算，你的答案應該會跟我一樣吧？
第一題. 0.3
第二題. 0.1
第三題. 6.9
上面應該是無庸置疑的答案，但是如果我們把這三個題目丟給Javascript去運算之後，得到的結果會變成這樣：
第一題. 0.1 + 0.2 = 0.30000000000000004
第二題. 1 – 0.9 = 0.09999999999999998
第三題. 0.69 x 10 = 6.8999999999999995
什麼！？Javascript連這種小學生的算術都會算錯嗎？其實是有原因的，Javascript所有數字都是以64位浮點數形式儲存，也就是所有的數字都會變轉換成二進位。
上面題目中特別有提到這是3個十進位的數學運算，這也就是這個題目的重點，如果今天的題目改成：10 / 3 = 3.3333333333333334 也許你就能比較明白了，也就是說在十進位中要表達 1 / 3 和二進位中表達 1 / 10 一樣困難。
但其實在我們設計網頁的過程中，使用者是沒有二進位觀念的，只在乎運算出來的數值是否符合十進位的結果，這個時候我們可以利用一些技巧來達成正確的結果。
方法1 . 將小數變成整數後再進行運算
第一題. ((0.1 x 10) + (0.2 x 10)) / 10 = 0.3
第二題. ((1 x 10) – (0.9 x 10)) / 10 = 0.1
第三題. ((0.69 x 100) x 10 / 100) = 6.9
雖說以上的方法能夠順利完成任務，但若運算的數值是動態（Dynamic）的，乘數的部分就比較難下，所以我們可以採用第二種方法。
方法2. Math.js（https://mathjs.org/）
透過網站上提供的js，或是透過CDN（https://cdnjs.com/libraries/mathjs）來引入後，透過以下的方法，就可以正確計算出上面三個題目的結果，其中14指的是精準度，通常已經很夠用了。
第一題. math.format(0.1 + 0.2 , 14) = 0.3
第一題. math.format(1 – 0.9 , 14) = 0.1
第一題. math.format(0.69 x 10 , 14) = 6.9
其實Math.js還有很多好用的功能，可以到它官方的網站閱讀一些文章，基本上所有的數學運算應該都可以透過它來玩完成。
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“You have a government that is reckless about what is going to happen to Guyana,” said Melinda Janki, an international lawyer in Guyana who is handling several lawsuits against Exxon. It’s pursuing “a supposed course of development that is actually backward and destructive,” she told CNN.
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And while plenty of Guyanese people welcome the new oil industry, some say Guyana’s startling economic statistics do not reflect a real-world prosperity for ordinary people, many of whom are struggling with the higher prices accompanying the oil boom. Inflation rose 6.6% in 2023, with prices of some foods shooting up much more rapidly.
“Since the oil extraction began in Guyana, we have noticed that our cost of living has gone sky high,” said Wintress White, of Red Thread, a non-profit that focuses on improving living conditions for Guyanese women. “The money is not trickling down to the masses,” she told CNN.
CNN contacted President Ali, the Ministry of Natural Resources and the Ministry of Finance for comment but received no response.
Guyana, a former Dutch then British colony which gained independence in 1966, is one of only a handful of countries that is a “carbon sink,” meaning it stores more planet-heating pollution than it produces. This is due to its vast rainforest; trees remove carbon dioxide from the atmosphere as they grow.
The country has protected its biodiversity where others have destroyed theirs, President Ali said in a BBC interview last year. In 2009, the country signed an agreement with Norway, which promised Guyana more than $250 million to preserve its 18.5 million hectares, or nearly 46 million acres, of forests.
Ali insists the country can balance climate leadership and fossil fuel exploitation. The new oil wealth will allow Guayana to develop, including building climate adaptations such as sea walls, he has said. He has also pointed to the continued failures of wealthy countries, already grown rich on their own fossil fuels, to help poorer countries with climate finance.
But there are concerns Guyana could fall victim to the “resource curse,” in which vast, new wealth ?can actually make life worse for those who live there.
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A tiny rainforest country is growing into a petrostate. A US oil company could reap the biggest rewards
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Guyana’s destiny changed in 2015. US fossil fuel giant Exxon discovered nearly 11 billion barrels of oil in the deep water off the coast of this tiny, rainforested country.
It was one of the most spectacular oil discoveries of recent decades. By 2019, Exxon and its partners, US oil company Hess and China-headquartered CNOOC, had started producing the fossil fuel.? They now pump around 650,000 barrels of oil a day, with plans to more than double this to 1.3 million by 2027.
Guyana now has the world’s highest expected oil production growth through 2035.
This country — sandwiched between Brazil, Venezuela and Suriname — has been hailed as a climate champion for the lush, well-preserved forests that carpet nearly 90% of its land. It is on the path to becoming a petrostate at the same time as the impacts of the fossil fuel-driven climate crisis escalate.
While the government says environmental protection and an oil industry can go hand-in-hand, and low-income countries must be allowed to exploit their own resources, critics say it’s a dangerous path in a warming world, and the benefits may ultimately skew toward Exxon — not Guyana.
Since Exxon’s transformative discovery, Guyana’s government has tightly embraced oil as a route to prosperity. In December 2019, then-President David Granger said in a speech, “petroleum resources will be utilized to provide the good life for all … Every Guyanese will benefit.”
It’s a narrative that has continued under current President Mohamed Irfaan Ali, who says new oil wealth will allow Guyana to develop better infrastructure, healthcare and climate adaptation.
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The voice of ‘White Lotus’ star Walton Goggins is the lullaby we didn’t know we needed
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While his “White Lotus” character Rick has been the source of some stress this season, Walton Goggins is here to soothe us into a state of dreamy sleep to make up for it.
The actor has partnered with relaxation and meditation app Calm for one of their famed Sleep Stories, lending his smoky voice to a fable titled “The Yard Sale.”
Goggins announced the Sleep Story on his verified Instagram on Tuesday, writing, “A friend once said to me the first question you ask someone shouldn’t be, ‘How are you?’ but rather, ‘How did you sleep last night?’ I agree.”
The post included an excerpt from the story, in which Goggins is heard languidly instructing listeners to relax their bodies and get into bed. “You could even climb into a hammock,” he added. “I wouldn’t do that because I’ve never gracefully got in or out of one.”
In the caption, the actor also wrote that he “wanted to create a Sleep Story that feels dreamlike, helping people slow their minds down by wandering through a yard sale (which happens to be one of my favorite things to do), uncovering hidden treasures.”
“It’s the Walton Goggins version of counting sheep. I hope you enjoy,” he added.
Other celebrities who have read bedtime stories in the hopes of putting audiences to sleep include Dolly Parton and the late Jimmy Stewart, whose voice was featured in a Calm Christmas Sleep Story in 2023 thanks to generative AI technology.
Goggins currently stars on “The White Lotus,” where his character is often the most stressed out and tortured of the ensemble, at one point setting a slew of snakes free.
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Of course, he said yes to coming back to the series, which eventually required him to live in Italy for a few months for filming.
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During production, White revealed to Gries that Greg is “very sinister.” That became rather irrefutable by the season’s climax, which saw Tanya’s demise orchestrated by her now-husband.
Come Season 3, Gries had to rewrite Greg’s backstory again, this time drawing from some unlikely sources for inspiration, like HBO docuseries “The Jinx,” about late convicted killer Robert Durst, and the case involving the man who came to be known as the Tinder Swindler.
Gries said he was struck by Durst’s “kind of seemingly even keel personality,” which served as a model for where Greg was headed, someone “who doesn’t really show a great deal of emotion, doesn’t seem to get too angry, just gets a little bit irritated and is dangerous.”
“There’s a bridled rage underneath. And those kind of people I find – at least with respect to Gary, Greg, Gary – fascinating,” he said.
And yet, while searching for an empathetic way back to portraying his character, Gries kept wondering if there was anything still redeeming about Greg.
An important “wake up moment” came during a decisive conversation he had with White just before filming in Thailand, in which the show’s creator said of Greg, in no uncertain terms: “He’s a psychopath.”
“And that was it. It was like, ‘back to the drawing board.’ And it really did help me,” Gries said.
The penultimate episode of the series will air on Sunday, an evening that thanks to “Lotus” and other shows has again become a night of appointment viewing amid a general move away from binge watching. Gries said he appreciates the shift.
“We’re a society that in a weird way doesn’t understand the beauty of waiting. The beauty of the space between the notes,” he shared. “If I binged (‘White Lotus’) I’d feel like I just ate too many chocolates. It just wouldn’t be the same. You need to process this.”
“The White Lotus” airs Sundays at 9 p.m. EDT on HBO, with the episode available to stream on Max. HBO and Max, like CNN, are owned by the same parent company, Warner Bros. Discovery.
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