按百分比计算损失和利润

Question

小提琴https://jsfiddle.net/o1hq1apw/2/

目前的BTC价格是2700美元。

7天的价格上涨了34%。

我持有3.011 BTC，如何计算我的利润？

currentPrice = 2700;
percent = 34;
holdings = 3.011;
alert(  calcPec(currentPrice,percent,holdings)  );

目前的BTC价格是2700美元。

价格在两天内上涨了-7%。

我持有3.011英镑，如何计算我的损失？

currentPrice = 2700;
percent = -7;
holdings = 3.011;
alert(  calcPec(currentPrice,percent,holdings)  );

// This is what i have but it is not correct
function calcPec(currentPrice,percent,holdings)
{
   res = currentPrice*percent/2;
   sum = holdings*res;
   return '$'+sum;
}

Answer 1

你忘了把百分比除以100才能得到分数。

​

// The current BTC price is 2700$.
// The price has increased by +34% in 7Days.
// I hold 3.011 BTC, how can i calculate my profit?

currentPrice = 2700;
percent = 34;
holdings = 3.011;
console.log(calcPec(currentPrice, percent, holdings));


// The current BTC price is 2700$.
// The price has increased by -7% in 2Days.
// I hold 3.011 BTC, how can i calculate my loss?

currentPrice = 2700;
percent = -7;
holdings = 3.011;
console.log(calcPec(currentPrice, percent, holdings));

function calcPec(currentPrice, percent, holdings) {
  const curr = holdings * currentPrice;
  const changed = curr * (1 + (percent / 100));
  return '$' + (changed - curr);
}

​

将来，您可能希望将百分比定义为一个分数，以避免出现这样的错误。所以你要做的不是percent = 34，而是percent = 0.34

编辑也修正了其他错误；

Answer 2

所以你持有3.011 BTC，目前是每个BTC 2700美元。7天前BTC的价格是100%，现在上涨了34%，所以2700美元相当于134%。要计算7天前的价格，你必须把2700除以134%，这大约是。2014年美元。所以你的收入是(2700-2014)* 3.011 =2065年

您的代码应该如下：

function calcPec(currentPrice, percent, holdings)
{
    oldPrice = currentPrice / ((100 + percent) / 100);
    sum = (currentPrice - oldPrice) * holdings;
}

Answer 3

您可以将百分比值除以100，再除以更改的百分比。

​

function calcPec(price, percent, holdings) {
    return '$' + (holdings * price * percent / 100).toFixed(2);
}

console.log(calcPec(2700, 34, 3.011));
console.log(calcPec(2700, -7, 3.011));

​