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JavaScript JavaScript Array Iteration Methods Array Manipulation Practice reduce()

Joseph Quintiliano
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Joseph Quintiliano
Front End Web Development Techdegree Graduate 14,338 Points
Posted by Joseph Quintiliano
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Joseph Quintiliano
Front End Web Development Techdegree Graduate 14,338 Points

Setting the reduce parameters into a variable and it wont accept it as an answer

once i copy and paste the callback to the reduce method itself, everything is fine. I would like to know if im breaking any rules while trying to code cleaner

app.js 
const phoneNumbers = ["(503) 123-4567", "(646) 123-4567", "(503) 987-6543", "(503) 234-5678", "(212) 123-4567", "(416) 123-4567"];
let numberOf503;

// numberOf503 should be: 3
// Write your code below
const x = (count, num) => {
  if (num.includes("503")){
    return count + 1;
  } return count
}, 0

numberOf503 = phoneNumbers.reduce(x);

1 Answer

Steven Parker
Steven Parker
231,269 Points
Steven Parker
Steven Parker
231,269 Points

There's a small syntax issue — the initial value for the count should be the 2nd argument to reduce (after the function). It's not part of the function definition. So, revising the code:

const x = (count, num) => {
  if (num.includes("503")) {
    return count + 1;
  }
  return count;
};                                         // no 0 here

numberOf503 = phoneNumbers.reduce(x, 0);   // the zero goes here

And if you're looking to make the code more concise, you might do this:

const x = (count, num) => count + num.includes("503");