Learn Advanced Array Methods by Building a Statistics Calculator - Step 35

Tell us what’s happening:

I feel like I’m going crazy here. I have checked all the forum posts and they’ve said that the ternary operator needs to be to the right of the assignment operator. I believe I have done that and my output appears to be correct in the console log but the test says I should be using a ternary operator.

Everyone who’s figured it out has said that it was a simple fix…

Your code so far

<!-- file: index.html -->
<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="utf-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1" />
    <link rel="stylesheet" href="./styles.css" />
    <script src="./script.js"></script>
    <title>Statistics Calculator</title>
  </head>
  <body>
    <h1>Statistics Calculator</h1>
    <p>Enter a list of comma-separated numbers.</p>
    <form onsubmit="calculate(); return false;">
      <label for="numbers">Numbers:</label>
      <input type="text" name="numbers" id="numbers" />
      <button type="submit">Calculate</button>
    </form>
    <div class="results">
      <p>
        The <dfn>mean</dfn> of a list of numbers is the average, calculated by
        taking the sum of all numbers and dividing that by the count of numbers.
      </p>
      <p class="bold">Mean: <span id="mean"></span></p>
      <p>
        The <dfn>median</dfn> of a list of numbers is the number that appears in
        the middle of the list, when sorted from least to greatest.
      </p>
      <p class="bold">Median: <span id="median"></span></p>
      <p>
        The <dfn>mode</dfn> of a list of numbers is the number that appears most
        often in the list.
      </p>
      <p class="bold">Mode: <span id="mode"></span></p>
      <p>
        The <dfn>range</dfn> of a list of numbers is the difference between the
        largest and smallest numbers in the list.
      </p>
      <p class="bold">Range: <span id="range"></span></p>
      <p>
        The <dfn>variance</dfn> of a list of numbers measures how far the values
        are from the mean, on average.
      </p>
      <p class="bold">Variance: <span id="variance"></span></p>
      <p>
        The <dfn>standard deviation</dfn> of a list of numbers is the square
        root of the variance.
      </p>
      <p class="bold">
        Standard Deviation: <span id="standardDeviation"></span>
      </p>
    </div>
  </body>
</html>
/* file: styles.css */
body {
  margin: 0;
  background-color: rgb(27, 27, 50);
  text-align: center;
  color: #fff;
}

button {
  cursor: pointer;
  background-color: rgb(59, 59, 79);
  border: 3px solid white;
  color: white;
}

input {
  background-color: rgb(10, 10, 35);
  color: white;
  border: 1px solid rgb(59, 59, 79);
}

.bold {
  font-weight: bold;
}
/* file: script.js */
const getMean = (array) => array.reduce((acc, el) => acc + el, 0) / array.length;

const getMedian = (array) => {
  const sorted = array.sort((a, b) => a - b);
  const median =
    array.length % 2 === 0
      ? getMean([sorted[array.length / 2], sorted[array.length / 2 - 1]])
      : sorted[Math.floor(array.length / 2)];
  return median;
}


// User Editable Region

const getMode = (array) => {
  const counts = {};
  array.forEach(el => counts[el] = counts[el] ? counts[el] += 1 : 1);
  console.log(counts);
  return counts;
}

// User Editable Region


const calculate = () => {
  const value = document.querySelector("#numbers").value;
  const array = value.split(/,\s*/g);
  const numbers = array.map(el => Number(el)).filter(el => !isNaN(el));
  
  const mean = getMean(numbers);
  const median = getMedian(numbers);
  console.log(getMode(numbers));

  document.querySelector("#mean").textContent = mean;
  document.querySelector("#median").textContent = median;
}

Your browser information:

User Agent is: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/18.2 Safari/605.1.15

Challenge Information:

Learn Advanced Array Methods by Building a Statistics Calculator - Step 35

Yes, it’s simple, it’s a matter of understanding what you want to do, and what it’s actually doing.

I appreciate the reply, Paulo, but it would be more beneficial if you pointed out a problem in the script. My script works, but it just doesn’t pass the test for some reason. Here’s the screenshot showing that an input of 6, 6, 7, 7 does log the correct counts:

this is an assignment and is inside the ternary
you need to add one without reassignment inside the ternary as the assignment already happen once the ternary is resolved

Thank you @ILM. Is this just best practice or is it a requirement? My script appears to work with this operator within the ternary.

if that is the expression evaluated, the expression is akin to counts[el] = counts[e] += 1, even if it works it is not good practice and quite redundant