> Typescript has always included extensions in the output of imports. When you used a bare TS file import without an extension it added a .js extension in the t

> Typescript has always included extensions in the output of imports. When you used a bare TS file import without an extension it added a .js extension in the transpiled output. .js file extensions have always worked in Typescript (going back to 0.x days). It was not. https://github.com/microsoft/TypeScript/issues/16577 https://github.com/microsoft/TypeScript/issues/16577 There was proposal and PR, but It was rejected. When writing ESM in typescript, you need to import with .js extension. >There's (luckily) no such thing as an "ESM variant" of Node and browsers will never have to know anything about the .mjs file extension. (Web servers will to make sure the present the right mime type, but that's a separate issue.) They just need ESM. I stand by accusing Node of doing the silly thing by adding the .cjs and .mjs file extensions. (I understand why they did it and mixed-module libraries were a thing that needed to exist until LTS support for ESM was well adopted, but we're past that transition phase, it wasn't that long of a transition phase, and in hindsight I think it still feels a little silly. Useful, but silly.) There is absolutely such thing. Spec is either intentionally not being followed (babel) or it allows for host implementation to define some things (node.js, deno). > but we're past that transition phase, We are not. 99% of new projects use ESM with CommonJS resolution today!. Most codebases have no way to transition to ESM. It was a Herculean effort for typescript codebase to be migrated into ESM https://devblogs.microsoft.com/typescript/typescripts-migration-to-modules/ https://devblogs.microsoft.com/typescript/typescripts-migrat... in March this year!.