CODEWITHSUNDEEP
javascriptreactjs
LeCoda
LeCoda

Reputation: 1026

javascript function, won't return to values?

I'm trying to simplify a javascript function so it's more readable

Currently I'm trying to change this function below.

export default function generateSentimentLineGraphPoints(items) {
  /**
   * Generate array of 24 Zeros
   */
  let values = Array.apply(null, Array(24)).map(Number.prototype.valueOf, 0);
  const nOfEntries = Array.apply(null, Array(24)).map(
    Number.prototype.valueOf,
    1
  ); 
.....
}

to more simply use this function,

function generateTime() {
  /**
   * Generate array of 24 Zeros
   */
  let values = Array.apply(null, Array(24)).map(Number.prototype.valueOf, 0);
  const nOfEntries = Array.apply(null, Array(24)).map(
    Number.prototype.valueOf,
    1
  );
  return values, nOfEntries;
}

with,

function generateTime() {
  /**
   * Generate array of 24 Zeros
   */
  let values = Array.apply(null, Array(24)).map(Number.prototype.valueOf, 0);
  const nOfEntries = Array.apply(null, Array(24)).map(
    Number.prototype.valueOf,
    1
  );
  return values, nOfEntries;
}

This isn't working for some reason - i'm not sure why, it won't load the graph properly. Any ideas?

Upvotes: 0

Views: 42

Answers (1)

T.J. Crowder
T.J. Crowder

Reputation: 1075597

return values, nOfEntries; returns the value of nOfEntries, it doesn't return values at all. A JavaScript function can only return one thing. You're using the comma operator there, which evaluates its left-hand operand (values), throws away the result, then evaluates its right-hand operator (nOfEntries) and takes that result as the operation result.

To return multiple values, wrap them in an array or object:

return [values, nOfEntries];

or

return {values, nOfEntries};

Side note: That code to create an array filled with a given value is unnecessarily complex. Back in the day it probably should have just been a function that uses a loop, but these days you can use Array.prototype.fill:

let values = Array(24).fill(0);

Upvotes: 1

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