fix(request): return empty string for empty catch-all param

src/hono.test.ts

@@ -3658,3 +3658,17 @@ describe('app.basePath() with the internal #clone()', () => {
     expect(await res.text()).toBe('Custom error "API Test error"')
   })
 })
+
+describe('Catch-all route with empty segment', () => {
+  it('Should return empty string for empty catch-all param', async () => {
+    const app = new Hono()
+    app.get('/:remaining{.*}', (c) => {
+      const remaining = c.req.param('remaining')
+      return c.json({ type: typeof remaining, value: remaining })
+    })
+    const res = await app.request('http://localhost/')
+    expect(res.status).toBe(200)
+    const json = await res.json()
+    expect(json).toEqual({ type: 'string', value: '' })
+  })
+})

src/request.test.ts

@@ -38,6 +38,21 @@ describe('Query', () => {
 })
 
 describe('Param', () => {
+  test('req.param() should return empty string for zero-length match', () => {
+    // Simulate a route like '/:remaining{.*}' matching '/'
+    const rawRequest = new Request('http://localhost/')
+    const req = new HonoRequest<'/:remaining{.*}'>(rawRequest, '/', [
+      [[[undefined, {} as RouterRoute], { remaining: 0 }]],
+      [''], // ParamStash with empty string for remaining
+    ])
+
+    // Single param access should be empty string, not undefined
+    expect(req.param('remaining')).toBe('')
+
+    // All params should include key with empty string value
+    const all = req.param()
+    expect(all).toEqual({ remaining: '' })
+  })
   test('req.param() with ParamStash', () => {
     const rawRequest = new Request('http://localhost?page=2&tag=A&tag=B')
     const req = new HonoRequest<'/:id/:name'>(rawRequest, '/123/key', [
@@ -72,6 +87,24 @@ describe('Param', () => {
     expect(req.param('id')).toBe('456')
     expect(req.param('name')).toBe('key')
   })
+
+  test('req.param() returns empty string for missing param', () => {
+    const rawRequest = new Request('http://localhost')
+    const req = new HonoRequest<'/:remaining'>(rawRequest, '/', [
+      [[[undefined, {} as RouterRoute], { remaining: 0 }]],
+      [''],
+    ])
+    expect(req.param('remaining')).toBe('')
+  })
+
+  test('req.param() without argument returns object with empty string for missing param', () => {
+    const rawRequest = new Request('http://localhost')
+    const req = new HonoRequest<'/:remaining'>(rawRequest, '/', [
+      [[[undefined, {} as RouterRoute], { remaining: 0 }]],
+      [''],
+    ])
+    expect(req.param()).toEqual({ remaining: '' })
+  })
 })
 
 describe('matchedRoutes', () => {

src/request.ts

@@ -98,7 +98,7 @@ export class HonoRequest<P extends string = '/', I extends Input['out'] = {}> {
   #getDecodedParam(key: string): string | undefined {
     const paramKey = this.#matchResult[0][this.routeIndex][1][key]
     const param = this.#getParamValue(paramKey)
-    return param ? (/\%/.test(param) ? tryDecodeURIComponent(param) : param) : undefined
+    return param && /\%/.test(param) ? tryDecodeURIComponent(param) : param
   }
 
   #getAllDecodedParams(): Record<string, string> {
@@ -107,7 +107,7 @@ export class HonoRequest<P extends string = '/', I extends Input['out'] = {}> {
     const keys = Object.keys(this.#matchResult[0][this.routeIndex][1])
     for (const key of keys) {
       const value = this.#getParamValue(this.#matchResult[0][this.routeIndex][1][key])
-      if (value && typeof value === 'string') {
+      if (value !== undefined) {
         decoded[key] = /\%/.test(value) ? tryDecodeURIComponent(value) : value
       }
     }