Considering anything that transpiled to ES5 would have to use var anyway, I'm curious why this was done in the source itself and not as a plugin/build step.
Considering anything that transpiled to ES5 would have to use var anyway, I'm curious why this was done in the source itself and not as a plugin/build step.
The post links to a TS issue [1] that explains
> As of TypeScript 5.0, the project's output target was switched from es5 to es2018 as part of a transition to ECMAScript modules. This meant that TypeScript could rely on the emit for native (and often more-succinct) syntax supported between ES2015 and ES2018. One might expect that this would unconditionally make things faster, but surprise we encountered was a slowdown from using let and const natively!
So they don't transpile to ES5, and that is the issue.
1: https://github.com/microsoft/TypeScript/issues/52924