GUIDE: how to sum an array

[dynabler]

Scenario: a page where you can buy a pair of shoes from a list of resellers. The resellers show how many pairs they have in stock. It looks something like this:

BUY THIS ITEM

• AmazingFlex (12 in stock)
• RockSneakers (9 in stock)
• CaliforniaJumps (17 in stock)

You use Flyscrape .map to get all the numbers (12, 9, 17)
You can use the following code to get a sum of 12 + 9 + 17

export default function({ doc, absoluteURL }) {
  const title = doc.find('h1');
  const stock_single = doc.find('.seller-section > div:nth-child(4)').map(stock => stock.text().split('\n')[6]);
  // calculate all stock
  // assign stock_single as map for our next calculation, returns ["12","9","17"]
  let myNums = stock_single;
  // create a variable for the sum and initialize it
  let sum = 0;
  // iterate over each item in the array stock_single
  for (let i = 0; i < +myNums.length; i++ ) {
  sum += +myNums[i];
// notice the + before myNums. Flyscrape returns an array of strings, and using + we change data type to Numbers
}
return {
    title: title.text().trim(),
    stock_single: likes_single, // shows an array  ["12","9","17"]
    stock: sum.toString(), // shows 38, convert back to string shows "38"
}