fix(useVModel): return default value when it's nil only (#1567)

package.json

@@ -21,7 +21,7 @@
     "publish:ci": "esno scripts/publish.ts",
     "install-fonts": "gfi install Inter && gfi install Fira Code",
     "release": "esno scripts/release.ts && git push --follow-tags",
-    "size": " esno scripts/export-size.ts",
+    "size": "esno scripts/export-size.ts",
     "test": "nr test:3",
     "test:2": "vue-demi-switch 2 vue2 && vitest run --silent",
     "test:3": "vue-demi-switch 3 && vitest run",

packages/core/useVModel/index.test.ts

@@ -107,10 +107,22 @@ describe('useVModel', () => {
   it('should work with user define defaultValue', () => {
     const props = {
       ...defaultProps(),
+      data: undefined as string | undefined,
+      a: 0,
+      b: '',
+      c: false,
     }
     const emitMock = vitest.fn()
+
     const data = useVModel(props, 'data', emitMock, { defaultValue: 'default-data' })
+    const dataA = useVModel(props, 'a', emitMock)
+    const dataB = useVModel(props, 'b', emitMock)
+    const dataC = useVModel(props, 'c', emitMock)
+
     expect(data.value).toBe('default-data')
+    expect(dataA.value).toBe(0)
+    expect(dataB.value).toBe('')
+    expect(dataC.value).toBe(false)
   })
 
   it('should work with user define defaultValue with passive', () => {

packages/core/useVModel/index.ts

@@ -71,7 +71,7 @@ export function useVModel<P extends object, K extends keyof P, Name extends stri
   event = eventName || event || `update:${key}`
 
   if (passive) {
-    const proxy = ref<P[K]>(props[key!] || defaultValue!)
+    const proxy = ref<P[K]>(props[key!] ?? defaultValue!)
 
     watch(() => props[key!], v => proxy.value = v as UnwrapRef<P[K]>)