What's New in JavaScript (ES 2020) - Part I
summary
Walks a real expense-tracking JSON app through concrete ES6+ rewrites and proves behavior with tests: refactors expense-tracker JSON app into a map-of-maps to preserve typed keys, replaces var with let/const and pushes many locals to const, and uses default parameters and for...of to simplify argument handling and iteration. Test suite runs after each change; most refactors keep all tests green while one edge case fails and is deferred to Part II.
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chapters (11)
- 0:00Introduction and setup
- 2:50JavaScript release cycle
- 3:55Expense tracking problem
- 7:52Refactoring with let and const
- 14:15Default and rest parameters
- 21:34Objects vs Maps in JavaScript
- 27:42Converting objects to Maps
- 33:59Initializing category totals
- 40:11Aggregating expenses with for...of
- 47:22Updating Map with expense totals
- 50:30Summary and next steps
