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JavaScript JavaScript Array Iteration Methods Array Manipulation Practice reduce()

Aziz Kemal HOSCAN
.a{fill-rule:evenodd;}techdegree seal-36
Aziz Kemal HOSCAN
Full Stack JavaScript Techdegree Graduate 16,113 Points

Unable to build conditional statement

I am pretty sure that the problem is my conditional statement. I tried different codes but still unable solve the problem. Please help

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
numberOf503 = phoneNumbers.reduce((count, number) => {
  if(number.slice(1,4) === '/(503)/') {
    return count + 1;
  return count;
}, 0);

1 Answer

Sean T. Unwin
Sean T. Unwin
28,690 Points

You are correct that the issue is with your conditional statement.

The issue is:

  • Conflating RegExp syntax, with the slashes, within a String i.e. '/(503)/'
  • number.slice(1,4) does not include the area code brackets, only the characters between

There two (2) ways to accomplish what you want.

  1. RegExp function test() - [Reference at MDN]

    • /503/.test(number.slice(1,4))
  2. Static String check, similar to what you have now without the RegExp slashes as well as brackets

    • number.slice(1,4) === '503'