refactor!: allow reorder "" suffix

Author: pi0

README.md

@@ -13,7 +13,7 @@ This library exposes an API similar to [`import.meta.resolve`](https://nodejs.or
 - Throws an error (or [try](#try)) if the resolved path does not exist in the filesystem.
 - Can override the default [conditions](#conditions).
 - Can resolve [from](#from) one or more parent URLs.
-- Can resolve with implicit `/index` [suffixes](#suffixes) as fallback.
+- Can resolve with custom [suffixes](#suffixes).
 - Can resolve with implicit [extensions](#extensions) as fallback.
 
 ## Usage
@@ -66,7 +66,7 @@ You can create a custom resolver instance with default [options](#resolve-option
 import { createResolver } from "exsolve";
 
 const { resolveModuleURL, resolveModulePath } = createResolver({
-  suffixes: ["/index"],
+  suffixes: ["", "/index"],
   extensions: [".mjs", ".cjs", ".js", ".mts", ".cts", ".ts", ".json"],
   conditions: ["node", "import", "production"],
 });
@@ -166,14 +166,14 @@ const src = resolveModulePath("./src/index", {
 
 ### `suffixes`
 
-Additional path suffixes to check as fallbacks.
+Path suffixes to check.
 
 **Example:**
 
 ```ts
 // "/app/src/utils/index.ts"
 const src = resolveModulePath("./src/utils", {
-  suffixes: ["/index"],
+  suffixes: ["", "/index"],
   extensions: [".mjs", ".cjs", ".js"],
 });
 ```
@@ -190,7 +190,7 @@ Resolve cache (enabled by default with a shared global object).
 
 Can be set to `false` to disable or a custom `Map` to bring your own cache object.
 
-See [cache](#cache) for more info.
+See [cache](#resolve-cache) for more info.
 
 ## Other Performance Tips
 

src/resolve.ts

@@ -41,7 +41,7 @@ export type ResolveOptions = {
   cache?: boolean | Map<string, unknown>;
 
   /**
-   * Additional file extensions to check as fallbacks.
+   * Additional file extensions to check as fallback.
    * These are used only if the input does not have an explicit extension.
    * For better performance, use explicit extensions.
    */
@@ -55,8 +55,11 @@ export type ResolveOptions = {
   conditions?: string[];
 
   /**
-   * Additional path suffixes to check as fallbacks.
-   * Suffix fallbacks are skipped if the input ends with the same suffix.
+   * Path suffixes to check.
+   * Suffixes are skipped if the input ends with the same suffix.
+   *
+   * @example ["", "/index"]
+   *
    * For better performance, use explicit suffix like `/index` when needed.
    */
   suffixes?: string[];
@@ -162,26 +165,19 @@ export function resolveModuleURL<O extends ResolveOptions>(
   const urls: URL[] = _normalizeResolveParents(options?.from);
   let resolved: URL | undefined;
 
-  const extensionsToCheck = (extname(id) === "" /* no extension */ &&
-    options?.extensions) || [""];
+  const suffixesToCheck = options?.suffixes || [""];
 
-  const suffixesToCheck = ["", ...(options?.suffixes || [])];
+  const extensionsToCheck =
+    extname(id) === "" /* no extension */
+      ? ["", ...(options?.extensions || [])]
+      : [""];
 
   for (const url of urls) {
-    // Try simple resolve
-    resolved = _tryModuleResolve(id, url, conditionsSet);
-    if (resolved) {
-      break;
-    }
-    // Try other extensions and suffixes if not found
     for (const suffix of suffixesToCheck) {
       if (suffix && id.endsWith(suffix)) {
         continue;
       }
       for (const extension of extensionsToCheck) {
-        if (!suffix && !extension) {
-          continue;
-        }
         resolved = _tryModuleResolve(
           `${id}${suffix}`.replace(/\/+/g, "/") + extension,
           url,

test/resolve.test.ts

@@ -21,7 +21,7 @@ const tests = [
 
 const extensions = [".mjs", ".cjs", ".js", ".mts", ".cts", ".ts", ".json"];
 
-const suffixes = ["/index"];
+const suffixes = ["", "/index"];
 
 describe("resolveModuleURL", () => {
   for (const test of tests) {