Learn Advanced Array Methods by Building a Statistics Calculator - Step 48

JavaScript
1

Tell us what’s happening:

I’m confused on which initial value to set to 0. Should it be in the sumSquaredDifferences variable or should it be in the callback function?

Your code so far

<!-- file: index.html -->


/* file: styles.css */


/* file: script.js */
// User Editable Region

const getVariance = (array) => {
  const mean = getMean(array);
  const differences = array.map(
    el => el - mean
  );
  const squaredDifferences = differences.map(
    el => el ** 2
  );
  const sumSquaredDifferences = squaredDifferences.reduce((acc, el) => acc + el);
}

// User Editable Region

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Challenge Information:

Learn Advanced Array Methods by Building a Statistics Calculator - Step 48

2

Hi @KoduFCC

Remember to set the initial value to 0 .

3

I know about the initial value, but I’m not sure about the position.

4

Check your previous code which uses the .reduce() method.

5

I figured it out finally. I just didn’t think right.

1 Like
6

That’s the solution, but the error message Your reduce callback should return the sum of acc and el is a bit misleading, being initialValue an optional argument :slight_smile: