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JavaScript JavaScript Array Iteration Methods Array Manipulation Practice reduce()

Aziz Kemal HOSCAN
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Aziz Kemal HOSCAN
Full Stack JavaScript Techdegree Graduate 16,113 Points
Posted by 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

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
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
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'