JavaScript in 2019
summary
Covers ES2019/ES10 additions and browser support details: new string methods trimStart/trimEnd; Object.fromEntries to rebuild objects from [key,value] arrays (overwrites duplicate keys); Array.prototype.flat with depth and flatMap; numeric separators for readability; optional catch binding; globalThis; private class fields using #; Function.prototype.toString preserves formatting; lookbehind in regex. Notes Promise.allSettled and Promise.any status varies across engines, Chrome implements many features (v72–77+), and Babel/Stage 3+ plugins transpile features back to ES5.
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chapters (12)
- 0:00Introduction
- 1:34JavaScript standards process
- 7:28New string methods
- 10:23Object from entries
- 14:50Array flat and flat map
- 20:04Promise allSettled and any
- 27:39Optional catch binding
- 29:56Global this value
- 31:45Private class fields
- 35:59Numeric separators and fixes
- 38:54Optional chaining future
- 39:16Q&A observables in JS
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