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JavaScript JavaScript Array Iteration Methods Array Manipulation Practice reduce()

Samuel Kleos
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.a{fill-rule:evenodd;}techdegree
Samuel Kleos
Front End Web Development Techdegree Student 12,719 Points

Why doesn't parseInt(number).toString() work?

Here is my initial solution:

numberOf503 = phoneNumbers.reduce((acc, phone) => (parseInt(phone).toString().substring(0, 3) === "503")? acc+1 : acc, 0);

Here is the solution that worked

numberOf503 = phoneNumbers.reduce((acc, phone) => (phone.substring(1, 4) === "503") ? acc+1 : acc, 0);
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
Rich Donnellan
Rich Donnellan
Treehouse Moderator 27,684 Points

I updated the question with code formatting hinting and fixed a typo in the title.

1 Answer

Steven Parker
Steven Parker
229,920 Points

Since all the phoneNumbers begin with a parenthesis, which is not a digit, then parseInt returns NaN.
That of course does not match "503".