Increase default tsc --init target over time

[JoshuaKGoldberg]

Suggestion

🔍 Search Terms

increase tsc init target es2016 default

✅ Viability Checklist

My suggestion meets these guidelines:

• This wouldn't be a breaking change in existing TypeScript/JavaScript code
• This wouldn't change the runtime behavior of existing JavaScript code
• This could be implemented without emitting different JS based on the types of the expressions
• This isn't a runtime feature (e.g. library functionality, non-ECMAScript syntax with JavaScript output, new syntax sugar for JS, etc.)
• This feature would agree with the rest of TypeScript's Design Goals.

⭐ Suggestion

As of 2022, all releases within the last year of browsers serving >0.1% of worldwide users support at least all of ECMAScript 2019 and nearly all of ECMAScript 2020-2021, while the LTS-supported versions of Node.js support all of ECMAScript 2021. There's very little reason not to have a target at least as high as "es2019".

How about increasing the default tsc --init value for target in later TypeScript versions over time to match the highest ECMAScript version supported by all LTS Node versions? That'd be "es2021" today.

📃 Motivating Example

Higher targets by default for consumers running tsc --init means they'll be able to use more language features as String.replaceAll by default. It's confusing to tsc --init, then not be able to use them.

💻 Use Cases

Increasing default targets to emit code much cleaner in modern runtimes gives a nicer default output for new TypeScript projects. For beginners to TypeScript in particular, it makes the learning curve a little easier as they won't have to mess with configuration options to be able to use basic features.

This issue is thematically similar to but not the same as #47572 and #47573. Those issue are about changing the default compiler options when no value is specified on the CLI or in a TSConfig file. This issue is about changing the target specified when using tsc --init.

[MartinJohns]

Related / duplicate in spirit: #39308