feat: support firebase@5

* index.js: docChanges is now a method The Firebase JS SDK introduced some breaking changes in 5.0.0: firebase/firebase-js-sdk@0997040 Fixes #183. * package.json: Update firebase peerDependency to 5.0.0 * Update package.json * Update index.js

Author: zhaofengli

src/index.js

@@ -119,12 +119,14 @@ function bindCollection ({
  }
  }
 
- const unbind = collection.onSnapshot(({ docChanges }) => {
+ const unbind = collection.onSnapshot((ref) => {
  // console.log('pending', metadata.hasPendingWrites)
  // docs.forEach(d => console.log('doc', d, '\n', 'data', d.data()))
  // NOTE this will only be triggered once and it will be with all the documents
  // from the query appearing as added
  // (https://firebase.google.com/docs/firestore/query-data/listen#view_changes_between_snapshots)
+ const docChanges = typeof ref.docChanges === 'function' ? ref.docChanges() : ref.docChanges
+
  if (!isResolved && docChanges.length) {
  // isResolved is only meant to make sure we do the check only once
  isResolved = true

test/helpers/mock.js

@@ -142,7 +142,7 @@ class CollectionReference extends callbacksAndErrors {
  setTimeout(() => {
  // Object.keys(this.data).map((k, i) => console.log(k, 'at', i, this.data[k].data))
  cb({
- docChanges: Object.keys(this.data).map((id, newIndex) => ({
+ docChanges: () => Object.keys(this.data).map((id, newIndex) => ({
  type: 'added',
  doc: new DocumentSnapshot(null, new Key(id), this.data[id].data),
  newIndex,
@@ -162,7 +162,7 @@ class CollectionReference extends callbacksAndErrors {
  index: Object.keys(this.data).length
  })
  this._callCallbacks({
- docChanges: [
+ docChanges: () => [
  {
  type: 'added',
  doc: new DocumentSnapshot(null, id, data),
@@ -194,7 +194,7 @@ class CollectionReference extends callbacksAndErrors {
  const ref = this.data[id.v]
  delete this.data[id.v]
  this._callCallbacks({
- docChanges: [
+ docChanges: () => [
  {
  doc: new DocumentSnapshot(null, id, ref.data),
  type: 'removed'
@@ -213,7 +213,7 @@ class CollectionReference extends callbacksAndErrors {
  type = 'added'
  }
  this._callCallbacks({
- docChanges: [
+ docChanges: () => [
  {
  type,
  doc: new DocumentSnapshot(null, id, data),