fix(runtime-dom): remove attrs with nullish values

fix #1576

packages/runtime-dom/__tests__/patchProps.spec.ts

@@ -107,4 +107,21 @@ describe('runtime-dom: props patching', () => {
 
     expect(`Failed setting prop "someProp" on <div>`).toHaveBeenWarnedLast()
   })
+
+  // #1576
+  test('remove attribute when value is falsy', () => {
+    const el = document.createElement('div')
+    patchProp(el, 'id', null, '')
+    expect(el.hasAttribute('id')).toBe(true)
+    patchProp(el, 'id', null, null)
+    expect(el.hasAttribute('id')).toBe(false)
+
+    patchProp(el, 'id', null, '')
+    expect(el.hasAttribute('id')).toBe(true)
+    patchProp(el, 'id', null, undefined)
+    expect(el.hasAttribute('id')).toBe(false)
+
+    patchProp(el, 'id', null, '')
+    expect(el.hasAttribute('id')).toBe(true)
+  })
 })

packages/runtime-dom/src/modules/props.ts

@@ -37,6 +37,7 @@ export function patchDOMProp(
   } else if (value == null && typeof el[key] === 'string') {
     // e.g. <div :id="null">
     el[key] = ''
+    el.removeAttribute(key)
   } else {
     // some properties perform value validation and throw
     try {