What's New in TypeScript 3.3 -- Visual Studio Magazine

What's New in TypeScript 3.3

By David Ramel
02/01/2019

The answer to the headline above is basically "not much," as Microsoft describes the new v3.3 update to TypeScript as "a smaller release than usual." But don't worry: TypeScript error messages may be displayed in haiku form in later releases, per one proposal on the roadmap.

A few new features that were mentioned by TypeScript guru Daniel Rosenwasser in an announcement blog post yesterday (Jan. 31) include improved behavior for calling union types, incremental file watching for composite projects and JavaScript editing in Sublime Text.

"Thanks to work done by former TypeScript team member Zhengbo Li and community contributor @idiotWu, our TypeScript plugin for Sublime Text now supports editing in JavaScript files!" Rosenwasser said of the latter new feature. "This means users will get more accurate completions, rename, go-to-definition, and more in JavaScript code that utilizes JSDoc and interoperates with TypeScript code."

Going forward, the TypeScript features roadmap shows more features on top to be introduced in v3.4, including:

Improved support for read-only arrays and tuples (checked off)
Const contexts for literal expressions (checked off)
Partial type argument inference
globalThis
Stricter types for IteratorResult
Quick fixes to Scaffold local @types packages
Refactorings to Convert to "named" parameters

Beyond that v.3.4 release that's scheduled for March, the "Future" features planned are:

Variadic types
Investigate nominal typing support
Flattening declarations
Implement ES Decorator proposal
Implement ES Private Fields
Investigate Ambient, Deprecated and Conditional decorators
Investigate error messages in haiku or iambic pentameter
Decorators for function expressions/arrow functions

And yes, you read that right: One of the future proposals is that "TypeScript error messages should always come in haiku form," publicized by Sarah Higley on March 13, 2018, and subsequently added to the roadmap by Rosenwasser.

**[Click on image for larger view.]** "TypeScript error messages should always come in haiku form." *(source: Twitter).*

Some examples of the form that such poetic error messages might take (though not actual error messages), posted on Twitter by Nick Nisi, include:

Command line options
You make my life so easy
Additional checks

My code is breaking
Ignore this error message
Everything is good

I don't like magic
Decorator expression
Let's change the standard

However, this reporter could find no corresponding issues for haiku or iambic parameter error message open issues on the GitHub site for TypeScript.

The idea may have sprung from a May 2017 post on ObjectComputing.com about "Flow -- JavaScript Type Checker."

That post demonstrates how to generate error messages from a haiku.txt file that appear like this:

Out of memory.
We wish to hold the whole sky,
But we never will.

Stay tuned for more on this TypeScript roadmap item.

About the Author

David Ramel is an editor and writer at Converge 360.

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