fix getOffset with function with test

js/src/dropdown.js

@@ -290,18 +290,14 @@ class Dropdown extends BaseComponent {
   }
 
   _getOffset() {
-    let { offset } = this._config
-
-    if (!offset) {
-      return [0, 0]
-    }
+    const { offset } = this._config
 
     if (typeof offset === 'string') {
-      offset = offset.split(',').map(val => Number.parseInt(val, 10))
-    } else if (typeof offset === 'function') {
-      offset = ({ popper, reference, placement }) => {
-        return offset({ popper, reference, placement }, this._element)
-      }
+      return offset.split(',').map(val => Number.parseInt(val, 10))
+    }
+
+    if (typeof offset === 'function') {
+      return popperData => offset(popperData, this._element)
     }
 
     return offset

js/tests/unit/dropdown.spec.js

@@ -54,7 +54,7 @@ describe('Dropdown', () => {
       expect(dropdown.toggle).toHaveBeenCalled()
     })
 
-    it('should create offset modifier correctly when offset option is a function', () => {
+    it('should create offset modifier correctly when offset option is a function', done => {
       fixtureEl.innerHTML = [
         '<div class="dropdown">',
         '  <button class="btn dropdown-toggle" data-bs-toggle="dropdown">Dropdown</button>',
@@ -64,14 +64,22 @@ describe('Dropdown', () => {
         '</div>'
       ].join('')
 
-      const getOffset = () => [10, 20]
+      const getOffset = jasmine.createSpy('getOffset').and.returnValue([10, 20])
       const btnDropdown = fixtureEl.querySelector('[data-bs-toggle="dropdown"]')
       const dropdown = new Dropdown(btnDropdown, {
-        offset: getOffset
+        offset: getOffset,
+        popperConfig: {
+          onFirstUpdate: state => {
+            expect(getOffset).toHaveBeenCalledWith({ ...state.rects, placement: state.placement }, btnDropdown)
+            done()
+          }
+        }
       })
       const offset = dropdown._getOffset()
 
       expect(typeof offset).toEqual('function')
+
+      dropdown.show()
     })
 
     it('should create offset modifier correctly when offset option is a string into data attribute', () => {