Port build dependencies from master into 4.x

.codesandbox/ci.json

@@ -0,0 +1,7 @@
+{
+  "sandboxes": [
+    "vanilla",
+    "vanilla-ts"
+  ],
+  "node": "14"
+}

.github/FUNDING.yml

@@ -0,0 +1 @@
+github: timdorr

.github/ISSUE_TEMPLATE/Bug_report.md

@@ -3,14 +3,41 @@ name: "\U0001F41BBug report"
 about: Something is wrong with Redux.
 ---
 
-**Do you want to request a _feature_ or report a _bug_?**
+<!--
+Thank you for contributing to open source!
 
-(If this is a _usage question_, please **do not post it here**—post it on [Stack Overflow](http://stackoverflow.com/questions/tagged/redux) instead. If this is not a “feature” or a “bug”, or the phrase “How do I...?” applies, then it's probably a usage question.)
+Do you need some help?
+======================
 
-**What is the current behavior?**
+The issue tracker is meant for bug reports only. This isn't the best place for support or usage questions. Questions here don't have as much visibility as they do elsewhere. Before you ask a question, here are some resources to get help first:
 
-**If the current behavior is a bug, please provide the steps to reproduce and if possible a minimal demo of the problem via https://jsfiddle.net or similar.**
+- Read the docs: https://redux.js.org/
+- Check out the troubleshooting guide: https://redux.js.org/troubleshooting
+- Look for/ask questions on Stack Overflow: https://stackoverflow.com/questions/tagged/redux
+- Ask in chat: https://www.reactiflux.com/
 
-**What is the expected behavior?**
+Think you found a bug?
+======================
+The best bug report is a failing test in the repository as a pull request. Otherwise, please use the template below.
 
-**Which versions of Redux, and which browser and OS are affected by this issue? Did this work in previous versions of Redux?**
+-->
+
+### Prior Issues
+
+Are there any existing issues or PRs that relate to this problem? If so, link them here.
+
+### What is the current behavior?
+
+What does Redux do right now.
+
+### Steps to Reproduce
+
+If the current behavior is a bug, please provide the steps to reproduce and if possible a minimal demo of the problem via https://codesandbox.io or similar.
+
+### What is the expected behavior?
+
+What should Redux be doing?
+
+### Environment Details
+
+Which versions of Redux, and which browser and OS are affected by this issue? Did this work in previous versions of Redux?

.github/ISSUE_TEMPLATE/Feature_request.md

@@ -0,0 +1,36 @@
+---
+name: 👍 Feature Request
+about: I'd like Redux to do something new.
+---
+
+<!--
+Thank you for contributing to open source!
+
+Do you need some help?
+======================
+
+The issue tracker is meant for feature requests and bug reports only. This isn't the best place for
+support or usage questions. Questions here don't have as much visibility as they do elsewhere. Before
+you ask a question, here are some resources to get help first:
+
+- Read the docs: https://redux.js.org/
+- Check out the troubleshooting guide: https://redux.js.org/troubleshooting
+- Look for/ask questions on Stack Overflow: https://stackoverflow.com/questions/tagged/redux
+- Ask in chat: https://www.reactiflux.com/
+
+Have a feature request?
+=======================
+Remove the template from below and provide thoughtful commentary *and code samples* on what this
+feature means for your product. What will it allow you to do that you can't do today? How will it
+make current work-arounds straightforward? What potential bugs and edge cases does it help to
+avoid? etc. Please keep it product-centric.
+
+-->
+
+## New Features
+
+### What is the new or updated feature that you are suggesting?
+
+### Why should this feature be included?
+
+### What docs changes are needed to explain this?

.github/ISSUE_TEMPLATE/config.yml

@@ -0,0 +1,5 @@
+blank_issues_enabled: false
+contact_links:
+    - name: 🤔 Questions and Help
+      url: https://redux.js.org/introduction/getting-started#help-and-discussion
+      about: This is a bug tracker, not a support system. For usage questions, please use our support resources.

.github/ISSUE_TEMPLATE/documentation-edit.md

@@ -0,0 +1,13 @@
+---
+name: "\U0001F4DD Documentation Fix"
+about: Fixing a problem in an existing docs page
+---
+
+## What docs page needs to be fixed?
+
+- **Section**:
+- **Page**:
+
+## What is the problem?
+
+## What should be changed to fix the problem?

.github/ISSUE_TEMPLATE/documentation-new.md

@@ -0,0 +1,27 @@
+---
+name: "\U0001F4D6 New/Updated Documentation Content"
+about: Adding a new docs page, or updating content in an existing docs page
+---
+
+## What docs page is being added or updated?
+
+- **Section**:
+- **Page**:
+
+## For Adding New Content
+
+### What kind of content category is this page (tutorial, how-to, explanation, reference)?
+
+### Who is the intended target audience?
+
+#### What knowledge are we assuming they have?
+
+### What are the intended results or takeaways from reading this page?
+
+### What is the most critical info they should learn?
+
+## For Updating Existing Content
+
+### What updates should be made to the page?
+
+### Do these updates change any of the assumptions or target audience? If so, how do they change?

.github/PULL_REQUEST_TEMPLATE.md

@@ -0,0 +1,9 @@
+Thanks for the PR!
+
+To better assist you, please select the type of PR you want to create.
+
+Click the "Preview" tab above, and click on the link for the PR type:
+
+- [:bug: Bug fix or new feature](?template=bugfix.md)
+- [:memo: Documentation Fix](?template=documentation-edit.md)
+- [:book: New/Updated Documentation Content](?template=documentation-new.md)

.github/PULL_REQUEST_TEMPLATE/bugfix.md

@@ -0,0 +1,34 @@
+---
+name: :bug: Bug fix or new feature
+about: Fixing a problem with Redux
+---
+
+## PR Type
+
+### Does this PR add a new _feature_, or fix a _bug_?
+
+### Why should this PR be included?
+
+## Checklist
+
+- [ ] Have you added an explanation of what your changes do and why you'd like us to include them?
+- [ ] Is there an existing issue for this PR?
+  - _link issue here_
+- [ ] Have the files been linted and formatted?
+- [ ] Have the docs been updated to match the changes in the PR?
+- [ ] Have the tests been updated to match the changes in the PR?
+- [ ] Have you run the tests locally to confirm they pass?
+
+## New Features
+
+### What new capabilities does this PR add?
+
+### What docs changes are needed to explain this?
+
+## Bug Fixes
+
+### What is the current behavior, and the steps to reproduce the issue?
+
+### What is the expected behavior?
+
+### How does this PR fix the problem?

.github/PULL_REQUEST_TEMPLATE/documentation-edit.md

@@ -0,0 +1,19 @@
+---
+name: :memo: Documentation Fix
+about: Fixing a problem in an existing docs page
+---
+
+## Checklist
+
+- [ ] Is there an existing issue for this PR?
+  - _link issue here_
+- [ ] Have the files been linted and formatted?
+
+## What docs page needs to be fixed?
+
+- **Section**:
+- **Page**:
+
+## What is the problem?
+
+## What changes does this PR make to fix the problem?

.github/PULL_REQUEST_TEMPLATE/documentation-new.md

@@ -0,0 +1,37 @@
+---
+name: :book: New/Updated Documentation Content
+about: Adding a new docs page, or updating content in an existing docs page
+---
+
+## PR Type
+
+**Does this PR add a _new_ page, or update an _existing_ page?**
+
+## Checklist
+
+- [ ] Is there an existing issue for this PR?
+  - _link issue here_
+- [ ] Have the files been linted and formatted?
+
+## What docs page is being added or updated?
+
+- **Section**:
+- **Page**:
+
+## For Adding New Content
+
+### What kind of content category is this page (tutorial, how-to, explanation, reference)?
+
+### Who is the intended target audience?
+
+#### What knowledge are we assuming they have?
+
+### What are the intended results or takeaways from reading this page?
+
+### What is the most critical info they should learn?
+
+## For Updating Existing Content
+
+### What updates should be made to the page?
+
+### Do these updates change any of the assumptions or target audience? If so, how do they change?

.github/workflows/size.yaml

@@ -0,0 +1,17 @@
+name: Bundle Size
+
+on: [pull_request]
+
+jobs:
+  build:
+    name: Check compressed size
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v2-beta
+        with:
+          fetch-depth: 1
+      - uses: preactjs/compressed-size-action@v1
+        with:
+          repo-token: '${{ secrets.GITHUB_TOKEN }}'
+          pattern: './{dist,es,lib}/*.js'

.github/workflows/test.yaml

@@ -0,0 +1,42 @@
+name: Tests
+
+on:
+  push:
+    branches: [4.x]
+  pull_request:
+    branches: [4.x]
+
+jobs:
+  build:
+    name: Test Suite
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Set up Node
+        uses: actions/setup-node@v1
+        with:
+          node-version: 14.x
+
+      - name: Checkout code
+        uses: actions/checkout@v2
+
+      - name: Cache dependencies
+        uses: actions/cache@v2
+        with:
+          path: ~/.npm
+          key: ${{ runner.OS }}-npm-${{ hashFiles('**/package-lock.json') }}
+          restore-keys: |
+            ${{ runner.OS }}-npm-
+            ${{ runner.OS }}-
+
+      - name: Install dependencies
+        run: npm ci
+
+      - name: Check formatting
+        run: npm run format:check
+
+      - name: Lint code
+        run: npm run lint
+
+      - name: Run test suite
+        run: npm test

docs/Troubleshooting.md

@@ -31,7 +31,7 @@ function todos(state = [], action) {
       // Wrong! This mutates state
       state.push({
         text: action.text,
-        completed: false
+        completed: false,
       })
       return state
     case 'COMPLETE_TODO':
@@ -55,16 +55,16 @@ function todos(state = [], action) {
         ...state,
         {
           text: action.text,
-          completed: false
-        }
+          completed: false,
+        },
       ]
     case 'COMPLETE_TODO':
       // Return a new array
       return state.map((todo, index) => {
         if (index === action.index) {
           // Copy the object before mutating
           return Object.assign({}, todo, {
-            completed: true
+            completed: true,
           })
         }
         return todo
@@ -82,7 +82,7 @@ It's more code, but it's exactly what makes Redux predictable and efficient. If
 return state.map((todo, index) => {
   if (index === action.index) {
     return Object.assign({}, todo, {
-      completed: true
+      completed: true,
     })
   }
   return todo
@@ -92,9 +92,9 @@ return state.map((todo, index) => {
 return update(state, {
   [action.index]: {
     completed: {
-      $set: true
-    }
-  }
+      $set: true,
+    },
+  },
 })
 ```
 
@@ -109,7 +109,7 @@ You can also enable the [object spread operator proposal](recipes/UsingObjectSpr
 return state.map((todo, index) => {
   if (index === action.index) {
     return Object.assign({}, todo, {
-      completed: true
+      completed: true,
     })
   }
   return todo