[Bug] Fix this binding in useChainCallback (#3252)

src/composables/functional/useChainCallback.ts

@@ -9,8 +9,8 @@ export const useChainCallback = <T extends (...args: any[]) => void>(
   originalCallback: T | undefined,
   ...callbacks: ((...args: Parameters<T>) => void)[]
 ) => {
-  return (...args: Parameters<T>) => {
-    originalCallback?.(...args)
-    callbacks.forEach((callback) => callback(...args))
+  return function (this: unknown, ...args: Parameters<T>) {
+    originalCallback?.call(this, ...args)
+    callbacks.forEach((callback) => callback.call(this, ...args))
   }
 }

tests-ui/tests/composables/functional/useChainCallback.test.ts

@@ -0,0 +1,55 @@
+import { describe, expect, it } from 'vitest'
+
+import { useChainCallback } from '@/composables/functional/useChainCallback'
+
+describe('useChainCallback', () => {
+  it('preserves "this" context in original callback and chained callbacks', () => {
+    class TestClass {
+      value = 'test'
+
+      constructor() {
+        this.method = useChainCallback(this.method, function (this: TestClass) {
+          expect(this.value).toBe('test')
+        })
+      }
+
+      method() {
+        expect(this.value).toBe('test')
+      }
+    }
+
+    const instance = new TestClass()
+    instance.method()
+  })
+
+  it('handles undefined original callback', () => {
+    const context = { value: 'test' }
+    const chainedFn = useChainCallback(
+      undefined,
+      function (this: typeof context) {
+        expect(this.value).toBe('test')
+      }
+    )
+
+    chainedFn.call(context)
+  })
+
+  it('passes arguments to all callbacks', () => {
+    const originalCalls: number[] = []
+    const chainedCalls: number[] = []
+
+    const original = function (this: unknown, num: number) {
+      originalCalls.push(num)
+    }
+
+    const chained = function (this: unknown, num: number) {
+      chainedCalls.push(num)
+    }
+
+    const chainedFn = useChainCallback(original, chained)
+    chainedFn(42)
+
+    expect(originalCalls).toEqual([42])
+    expect(chainedCalls).toEqual([42])
+  })
+})