Percentage difference between two numbers equals NaN - JavaScript

Question

I'm calculating the difference between the two numbers I am getting from an array. I would like to get the percentage difference between the two, so my logic behind it is: Original number / New Number * 100 = %

I have a console log for the original number as console.log(data.Results.Data[115].DataValue, "First") which shows 1,378,637.7

I have another console log for the new number as console.log(data.Results.Data[116].DataValue, "Second") which equals to 1,470,393.0

I am now trying to declare a variable that would equal the percentage between these two values.

let perChangeOne = data.Results.Data[116].DataValue / data.Results.Data[115].DataValue * 100 console.log(perChangeOne, "%%")

When the console.log for perChangeOne equals NaN. I am expecting to show 106.7

function drawPercentageDifference(data) {       
    let perChangeOne = data.Results.Data[116].DataValue / data.Results.Data[115].DataValue * 100
    console.log(perChangeOne, "%%")
    console.log(data.Results.Data[116].DataValue, "First")
    console.log(data.Results.Data[115].DataValue, "Second")
}

BEA was a typo, shouldve been removed. Edited text to reflect that — kurtixl, Apr 23 '20 at 20:21
@Estradiaz That does the same as `string / string`, giving `NaN` due to the `,`... `/` already coerces its operands to a number, same as the unary `+` does — CherryDT, Apr 23 '20 at 20:43
Does this answer your question? [Division produces NaN](https://stackoverflow.com/questions/15600132/division-produces-nan) — Heretic Monkey, Apr 23 '20 at 20:50
For the comma issue, [How can I parse a string with a comma thousand separator to a number?](https://stackoverflow.com/q/11665884/215552) — Heretic Monkey, Apr 23 '20 at 20:52

CherryDT · Accepted Answer · 2020-05-05T17:32:52.747

You values are probably strings, and due to the , they can't be coerced to a number.

You need to remove the ,. Even though it's not strictly necessary, I'd then convert to a number explicitly as well:

    function drawPercentageDifference(data) {
        const numerator = Number(data.Results.Data[116].DataValue.replace(/,/g, ''))
        const denominator = Number(data.Results.Data[115].DataValue.replace(/,/g, ''))
        const percentage = 100 * numerator / denominator
        console.log(`${percentage} % (${numerator} / ${denominator})`)
    }

Percentage difference between two numbers equals NaN - JavaScript

1 Answers1