🤑 Join the Treehouse affiliate program and earn 25% recurring commission!

New No-Code Track! 🚀start learning today!

🌟 Dreaming of a bright future? 🎓 Ask about the Treehouse Scholarship program! 🚀

✨ Earn college credits in Cybersecurity, JS, HTML, CSS and Python

  • Treehouse Logo
  • Plans
    Chevron
    • For Individuals
    • For Businesses
    • For Schools
    • For Libraries
    • For Military
  • Library
    Chevron
    • All Courses
    • Tracks
    • College Credit
  • Techdegree
    Chevron
    • Overview
    • Front End Development
    • Full Stack JavaScript
    • Data Analysis
    • UX Design
    • Python
  • Community
    Chevron
    • Code Adventures
    • Discord
    • Forum
    • Success Stories
    • Treehouse Links
    • 100 Days of Code
  • Resources
    Chevron
    • Career Toolbox
    • CodeForward
    • Free Treehouse Near Me
    • Jobs
    • Blog
    • Support
    • About
  • For Individuals For Businesses For Schools For Libraries For Military
  • All Courses Tracks College Credit
  • Overview Front End Web Development Full Stack JavaScript Python Development Data Analysis UX Design
  • Code Adventures Discord Forum Success Stories Treehouse Links 100 Days of Code
  • Career Toolbox CodeForward Free Treehouse Near Me Jobs Blog Support About
  • Sign In
  • Free Trial
Instagram Twitter Facebook YouTube LinkedIn
    • Newest
      • Newest
      • Active
      • Unanswered
      • Featured
    • All Topics
      • All Topics
      • • General Discussion
      • • AI
      • • Android
      • • APIs
      • • Coding for Kids
      • • College Credit
      • • Computer Science
      • • CSS
      • • Data Analysis
      • • Databases
      • • Design
      • • Development Tools
      • • Digital Literacy
      • • Game Development
      • • Go Language
      • • HTML
      • • Java
      • • JavaScript
      • • Learning Resources
      • • Machine Learning
      • • No-Code
      • • PHP
      • • Professional Growth
      • • Python
      • • Quality Assurance
      • • React
      • • Ruby
      • • Security
      • • Swift
  • Samuel Kleos
    seal-mask
    .a{fill-rule:evenodd;}techdegree
    Samuel Kleos
    Front End Web Development Techdegree Student 13,728 Points

    Confusion. . . 😵‍💫 Why is my daysOverDue property negative?

    Posted February 28, 2023 9:56pm by Samuel Kleos
    .a{fill-rule:evenodd;}techdegree
    Samuel Kleos
    Front End Web Development Techdegree Student 13,728 Points
    • JavaScript
    • Practice Object Interaction
    • Checking Out and Returning a Book
    • Solution: Charging Fines to Patrons

    1 Answer

  • Seth Missiaen
    seal-mask
    .a{fill-rule:evenodd;}techdegree seal-36
    Seth Missiaen
    Web Development Techdegree Graduate 21,652 Points

    Is the content inside "this.patrons.filter()" an arrow function?

    Posted March 23, 2022 1:56pm by Seth Missiaen
    .a{fill-rule:evenodd;}techdegree seal-36
    Seth Missiaen
    Web Development Techdegree Graduate 21,652 Points
    • JavaScript
    • Practice Object Interaction
    • Checking Out and Returning a Book
    • Solution: Charging Fines to Patrons

    1 Answer

  • Xun Huang
    seal-mask
    .a{fill-rule:evenodd;}techdegree seal-36
    Xun Huang
    Web Development Techdegree Graduate 18,515 Points

    WHY 'patron.balance += this.dailyFine * daysLate' ???

    Posted March 3, 2022 7:42pm by Xun Huang
    .a{fill-rule:evenodd;}techdegree seal-36
    Xun Huang
    Web Development Techdegree Graduate 18,515 Points
    • JavaScript
    • Practice Object Interaction
    • Checking Out and Returning a Book
    • Solution: Charging Fines to Patrons

    1 Answer

  • Johannes Deutsch
    seal-mask
    .a{fill-rule:evenodd;}techdegree seal-36
    Johannes Deutsch
    Full Stack JavaScript Techdegree Graduate 19,869 Points

    now

    Posted November 26, 2021 3:45pm by Johannes Deutsch
    .a{fill-rule:evenodd;}techdegree seal-36
    Johannes Deutsch
    Full Stack JavaScript Techdegree Graduate 19,869 Points
    • JavaScript
    • Practice Object Interaction
    • Checking Out and Returning a Book
    • Solution: Charging Fines to Patrons

    2 Answers

  • Farid Lavizadeh
    Farid Lavizadeh
    12,006 Points

    DayLate can't be correct.

    Posted August 18, 2020 5:28pm by Farid Lavizadeh
    Farid Lavizadeh
    12,006 Points
    • JavaScript
    • Practice Object Interaction
    • Checking Out and Returning a Book
    • Solution: Charging Fines to Patrons

    3 Answers

  • Brendan Moran
    Brendan Moran
    14,052 Points

    Is it ok to use a method to get a state *IF* I never, ever want to set that state?

    Posted July 28, 2020 2:36pm by Brendan Moran
    Brendan Moran
    14,052 Points
    • JavaScript
    • Practice Object Interaction
    • Checking Out and Returning a Book
    • Solution: Charging Fines to Patrons

    1 Answer

  • Faraz Khalid
    Faraz Khalid
    4,077 Points

    Practice Object Interaction

    Posted April 21, 2020 2:40am by Faraz Khalid
    Faraz Khalid
    4,077 Points
    • JavaScript
    • Practice Object Interaction
    • Checking Out and Returning a Book
    • Solution: Charging Fines to Patrons

    1 Answer

  • Michael Cook
    seal-mask
    .a{fill-rule:evenodd;}techdegree seal-36
    Michael Cook
    Full Stack JavaScript Techdegree Graduate 28,975 Points

    My chargeFines method

    Posted December 1, 2019 1:34am by Michael Cook
    .a{fill-rule:evenodd;}techdegree seal-36
    Michael Cook
    Full Stack JavaScript Techdegree Graduate 28,975 Points
    • JavaScript
    • Practice Object Interaction
    • Checking Out and Returning a Book
    • Solution: Charging Fines to Patrons

    1 Answer

  • Okle Odai
    seal-mask
    .a{fill-rule:evenodd;}techdegree
    Okle Odai
    Full Stack JavaScript Techdegree Student 10,816 Points

    How do I approach this challenge? My attempt was completely off from the actual solution.

    Posted November 22, 2019 9:14pm by Okle Odai
    .a{fill-rule:evenodd;}techdegree
    Okle Odai
    Full Stack JavaScript Techdegree Student 10,816 Points
    • JavaScript
    • Practice Object Interaction
    • Checking Out and Returning a Book
    • Solution: Charging Fines to Patrons

    1 Answer

  • fairest
    seal-mask
    .a{fill-rule:evenodd;}techdegree seal-36
    fairest
    Full Stack JavaScript Techdegree Graduate 19,303 Points

    Why would you first let us figure the chargeFines() function if the solution isn't really a solution?

    Posted November 16, 2019 4:03am by fairest
    .a{fill-rule:evenodd;}techdegree seal-36
    fairest
    Full Stack JavaScript Techdegree Graduate 19,303 Points
    • JavaScript
    • Practice Object Interaction
    • Checking Out and Returning a Book
    • Solution: Charging Fines to Patrons

    0 Answers

  • Dan Ingenthron
    Dan Ingenthron
    8,769 Points

    Is the code meant to charge the same fine for each day the book is late?

    Posted November 16, 2019 12:23am by Dan Ingenthron
    Dan Ingenthron
    8,769 Points
    • JavaScript
    • Practice Object Interaction
    • Checking Out and Returning a Book
    • Solution: Charging Fines to Patrons

    1 Answer

  • Juneau Lim
    Juneau Lim
    13,362 Points

    Where can I learn/practice functions like filter?

    Posted May 23, 2019 11:50am by Juneau Lim
    Juneau Lim
    13,362 Points
    • JavaScript
    • Practice Object Interaction
    • Checking Out and Returning a Book
    • Solution: Charging Fines to Patrons

    2 Answers

  • Muhammad Umar
    Muhammad Umar
    7,817 Points

    Using Console.log on const dateDiff gives the date Wed Jan 14 1970 18:00:00 GMT-0600 (Central Standard Time) ??

    Posted May 14, 2019 1:22pm by Muhammad Umar
    Muhammad Umar
    7,817 Points
    • JavaScript
    • Practice Object Interaction
    • Checking Out and Returning a Book
    • Solution: Charging Fines to Patrons

    2 Answers

  • Muhammad Umar
    Muhammad Umar
    7,817 Points

    Help: chargeFines() What would happen if this method was called more than once while a patron had the same book overdue?

    Posted April 21, 2019 5:34pm by Muhammad Umar
    Muhammad Umar
    7,817 Points
    • JavaScript
    • Practice Object Interaction
    • Checking Out and Returning a Book
    • Solution: Charging Fines to Patrons

    4 Answers

  • gerardo keys
    gerardo keys
    14,292 Points

    I don't understand parts of the chargeFines method.

    Posted April 16, 2019 7:24pm by gerardo keys
    gerardo keys
    14,292 Points
    • JavaScript
    • Practice Object Interaction
    • Checking Out and Returning a Book
    • Solution: Charging Fines to Patrons

    3 Answers

  • Nicholas Wallen
    Nicholas Wallen
    12,278 Points

    This part doesn't make sense to me. Can someone explain?

    Posted February 15, 2019 1:34am by Nicholas Wallen
    Nicholas Wallen
    12,278 Points
    • JavaScript
    • Practice Object Interaction
    • Checking Out and Returning a Book
    • Solution: Charging Fines to Patrons

    1 Answer

Posting to the forum is only allowed for members with active accounts.
Please sign in or sign up to post.

    Treehouse

  • About
  • Blog
  • Careers
  • Community
  • Stories
  • Shop
  • Contact
  • Gift Card

See Full Catalogue

Techdegree

  • Front End Web Development
  • Full Stack JavaScript
  • Python Development
  • Data Analysis
  • UX Design

Tracks

  • Learn to Code for Beginners
  • Beginning Python
  • Beginning SQL
  • Beginning Java
  • ...see more

Courses

  • JavaScript Basics
  • Intro to HTML & CSS
  • Python Basics
  • CSS Layout
  • ...see more

Explore

  • Plans
  • Affiliates
  • Perks
  • Free Treehouse Near Me
  • Treehouse for Libraries
  • Treehouse for Businesses
  • Twitter
  • YouTube
  • Facebook
  • LinkedIn
  • Instagram
Terms & Conditions | Privacy

© 2025 Treehouse Island, Inc.