diff --git a/html-meta.md b/html-meta.md
index cd731a5d1..58ac0daef 100644
--- a/html-meta.md
+++ b/html-meta.md
@@ -63,6 +63,20 @@ article:tag
 <link rel="icon" type="image/png" href="/assets/favicon.png">
 ```
 
+### Web app
+
+```html
+<meta name="mobile-web-app-capable" content="yes">
+<meta name="apple-mobile-web-app-capable" content="yes">
+<meta name="apple-mobile-web-app-status-bar-style" content="black"> <!-- black | black-translucent | default -->
+```
+
+### Apple-only
+
+```html
+<meta name="format-detection" content="telephone=no">
+```
+
 ### Reference
 
  * https://dev.twitter.com/docs/cards
diff --git a/jest.md b/jest.md
new file mode 100644
index 000000000..bb5450925
--- /dev/null
+++ b/jest.md
@@ -0,0 +1,120 @@
+---
+title: Jest
+category: JavaScript libraries
+---
+
+## Testing
+
+```js
+beforeEach(() => { ... })
+afterEach(() => { ... })
+
+beforeAll(() => { ... })
+afterAll(() => { ... })
+
+describe('My work', () => {
+  test('works', () => {
+    expect(2).toEqual(2)
+  })
+
+  test('works asynchonously', () => {
+    return new Promise((resolve, reject) => { ... })
+  })
+
+  test('works asynchonously', async () => {
+    const hello = await foo()
+    ...
+  })
+})
+```
+
+## Expect
+
+```js
+expect(value)
+  .not
+  .toBe(value)
+  .toEqual(value)
+
+  // Snapshots
+  .toMatchSnapshot()
+
+  // Errors
+  .toThrow(error)
+  .toThrowErrorMatchingSnapshot()
+
+  // Booleans
+  .toBeFalsy()
+  .toBeNull()
+  .toBeTruthy()
+  .toBeUndefined()
+  .toBeDefined()
+
+  // Numbers
+  .toBeCloseTo(number, numDigits)
+  .toBeGreaterThan(number)
+  .toBeGreaterThanOrEqual(number)
+  .toBeLessThan(number)
+  .toBeLessThanOrEqual(number)
+
+  // Objects
+  .toBeInstanceOf(Class)
+  .toMatchObject(object)
+  .toHaveProperty(keyPath, value)
+
+  // Arrays
+  .toContain(item)
+  .toContainEqual(item)
+  .toHaveLength(number)
+
+  // String
+  .toMatch(regexpOrString)
+```
+
+```js
+expect.extend(matchers)
+expect.any(constructor)
+expect.addSnapshotSerializer(serializer)
+
+expect.assertions(1)
+```
+
+## Snapshots
+
+```
+const tree = renderer.create(
+<Link page="http://www.facebook.com">Facebook</Link>
+).toJSON()
+
+// First run creates a snapshot; subsequent runs match it
+expect(tree).toMatchSnapshot()
+
+// To update snapshots: jest --updateSnapshot
+```
+
+## Mocks
+
+```js
+const fn = jest.fn()
+const fn = jest.fn(n => n * n)
+```
+
+```js
+expect(fn)
+  // Functions
+  .toHaveBeenCalled()
+  .toHaveBeenCalledTimes(number)
+  .toHaveBeenCalledWith(arg1, arg2, ...)
+  .toHaveBeenLastCalledWith(arg1, arg2, ...)
+
+  .toHaveBeenCalledWith(expect.anything())
+  .toHaveBeenCalledWith(expect.any(constructor))
+  .toHaveBeenCalledWith(expect.arrayContaining([ values ]))
+  .toHaveBeenCalledWith(expect.objectContaining({ props }))
+  .toHaveBeenCalledWith(expect.stringContaining(string))
+  .toHaveBeenCalledWith(expect.stringMatching(regexp))
+```
+
+## References
+
+Based on Jest v19. <http://facebook.github.io/jest/>