Convert the library to TypeScript and ship the types

[enyo]

src/dropzone.js, options.js, emitter.js and extend.js are now TypeScript, the build emits declarations into dist/, and package.json gains a types field.

This matters beyond tidiness: @types/dropzone is stuck at 5.7.9 and describes the v5 API, so every v6 TypeScript user today is either untyped or actively wrongly typed.

strict is on

tsc runs as part of build, so a type error fails the build. Clearing it took 285 errors. Most were mechanical — 162 parameters without annotations — but four were structural, and those are the ones worth reviewing:

this.options is typed as the merged result, not the user's partial input. There are now two types: DropzoneOptions is what you pass in (everything optional), ResolvedDropzoneOptions is what an instance holds (everything present, because the defaults have been merged). Reading an option through the Partial made every access | undefined for a value that is always there, and that accounted for most of the null-safety noise.

Options whose default is null are widened. typeof defaultOptions types url: null as exactly null, so assigning a string to it is an error. A mapped type widens those; every other option keeps the type its default implies, which is the whole point of deriving the type rather than writing it by hand.

The 14 option handlers that use this now declare it. Overriding one gets a typed Dropzone rather than the options literal — and it reaches the published declarations, so it types your code too:

const options: DropzoneOptions = {
  url: "/upload",
  init(this: Dropzone) { console.log(this.files.length); },
};

DropzoneFile.status and .upload are required, not optional. addFile sets both before anything reads them, so optional described a window no consumer ever sees.

The options type is derived, not written

type WidenNullDefaults<T> = { [K in keyof T]: null extends T[K] ? any : T[K] };
export type DropzoneOptions = Partial<WidenNullDefaults<typeof defaultOptions>> & Record<string, any>;

All 95 options follow src/options.ts by construction — nothing to hand-maintain, nothing that can drift. JSDoc comes through into the declarations, so editors show the documentation on hover.

DropzoneFile and DropzoneListener are type aliases rather than interfaces, as requested. There are no interfaces left in the source.

Verified from the outside

Compiling a consumer against dist/ under strict:

const dz = new Dropzone("#el", { url: "/upload", maxFilesize: 10, parallelUploads: 3 });
dz.on("addedfile", (file: DropzoneFile) => console.log(file.name, file.status, file.upload));

// @ts-expect-error maxFilesize is a number, so a string must be rejected
const bad: DropzoneOptions = { maxFilesize: "ten" };

Compiles clean — which also means the @ts-expect-error fired. Had the type been any, the directive would be unused and tsc would have failed.

252 tests and 3 end-to-end specs pass.

Two things the conversion found

Both behaviour-preserving:

Bitwise & between two comparisons. Three conditions in the EXIF code read (seg[0] === 255) & (seg[1] === 225), which only works by coercing booleans to 0/1. Both operands are pure comparisons, so && is exactly equivalent.

Dropzone.isValidFile assumed acceptedFiles was a string and called .split on it. An array was already reaching it and would have thrown; it is now accepted, as the signature says.

exports is deliberately not added

It is on the 7.0 list. Adding it now changes module resolution for every consumer, which is not a patch-level change. types sits next to main/module and is purely additive.

On src/types.d.ts

You said you saw no reason to maintain a separate types.d.ts, and this is not that — the API description is generated. This file declares things that are not in the source at all: vite's ?raw and ?inline imports, and the EXIF and jQuery globals, which the library only touches when the page already provides them.

[github-actions]

Coverage Report

Status	Category	Percentage	Covered / Total
🔵	Lines	79.42%	880 / 1108
🔵	Statements	79.77%	927 / 1162
🔵	Functions	92.89%	196 / 211
🔵	Branches	76.46%	510 / 667

File Coverage

File	Stmts	Branches	Functions	Lines	Uncovered Lines
Changed Files
packages/dropzone/src/types.d.ts	0%	0%	0%	0%

Generated in workflow #118 for commit 25d2f42 by the Vitest Coverage Report Action