Refactor design.js:model

[shijiezhou1]

I've selected design.js:model for refactoring, which is a unit of 25 lines of code. Addressing this will make our codebase more maintainable and improve Better Code Hub's Write Short Units of Code guideline rating! 👍

Here's the gist of this guideline:

• Definition 📖
  Limit the length of code units to 15 lines of code.
• Why❓
  Small units are easier to analyse, test and reuse.
• How 🔧
  When writing new units, don't let them grow above 15 lines of code. When a unit grows beyond this, split it in smaller units of no longer than 15 lines.

You can find more info about this guideline in Building Maintainable Software. 📖

---

ℹ️ To know how many other refactoring candidates need addressing to get a guideline compliant, select some by clicking on the 🔲 next to them. The risk profile below the candidates signals (✅) when it's enough! 🏁

---

Good luck and happy coding! ✨ 💯