Hasty Treat - Seven Interesting JavaScript Proposals - Async Do, JSON Modules, Immutable Array Methods, and More!
In this Hasty Treat, Scott and Wes talk about seven new JavaScript proposals — what they do, where they’re at, and how you might use them.
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Show Notes
03:32 - Seven new JavaScript proposals
06:25 - JSON Modules
- https://github.com/tc39/proposal-json-modules
- Builds on the import assertions
- No named exports
- Not executed, to avoid security issues
- Not in Node yet
09:55 - Array Find From Last
- https://github.com/tc39/proposal-array-find-from-last
- The problem: you need to group together async code.The only way to do that right now is to wrap it in a function.
11:40 - Async Do
- https://github.com/tc39/proposal-async-do-expressions
- Async do will allow you to group together a block of code and mark it as async.
- No need for an iife
- Downside to this is that it’s a code block, so if you need to return any values, you’ll need to jump that up a scope level.
Promise.all([ async do { let result = await fetch('thing A'); await result.json(); }, async do { let result = await fetch('thing B'); await result.json(); }, ]).then(([a, b]) => console.log([a, b])); 14:33 - Change Array By Copy
- https://github.com/tc39/proposal-change-array-by-copy
- Like old array methods, but returns a new array rather than mutating
17:48 - Temporal
- https://github.com/tc39/proposal-temporal
- Stage 3, looking good!
- Amazing, large, very good Date API
- Syntax 295: Hasty Treat — Temporal Date Objects in JavaScript
18:35 - As Patterns
- https://github.com/zkat/proposal-as-patterns
- Scott don’t get it
- Stage 0
- when ([ ‘go’, (‘north’ | ‘east’ | ‘south’ | ‘west’) as dir ]) { … }
20:47 - Pattern Matching
- https://github.com/tc39/proposal-pattern-matching
- VERY Rust-like
- Stage 1
{props => match (props) { when ({ loading }) { ; } when ({ error }) { ; } when ({ data }) { ; } }} Tweet us your tasty treats!
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