From 3fae7adc4ad19939c77d34a7e98460e573e960ff Mon Sep 17 00:00:00 2001
From: Jerko Steiner <jerko.steiner@gmail.com>
Date: Sun, 17 Mar 2019 19:42:26 +0500
Subject: [PATCH] Add isClientSide helper for server-side rendering

---
 packages/client/src/renderer/index.ts         |  1 +
 .../client/src/renderer/isClientSide.test.ts  | 27 +++++++++++++++++++
 packages/client/src/renderer/isClientSide.ts  |  5 ++++
 3 files changed, 33 insertions(+)
 create mode 100644 packages/client/src/renderer/isClientSide.test.ts
 create mode 100644 packages/client/src/renderer/isClientSide.ts

diff --git a/packages/client/src/renderer/index.ts b/packages/client/src/renderer/index.ts
index cb6e9f5..5614ea8 100644
--- a/packages/client/src/renderer/index.ts
+++ b/packages/client/src/renderer/index.ts
@@ -2,3 +2,4 @@ export * from './ClientRenderer'
 export * from './IClientConfig'
 export * from './IRenderer'
 export * from './IStoreFactory'
+export * from './isClientSide'
diff --git a/packages/client/src/renderer/isClientSide.test.ts b/packages/client/src/renderer/isClientSide.test.ts
new file mode 100644
index 0000000..8b20f80
--- /dev/null
+++ b/packages/client/src/renderer/isClientSide.test.ts
@@ -0,0 +1,27 @@
+import {isClientSide} from './isClientSide'
+
+describe('isClientSide', () => {
+
+  describe('client', () => {
+    it('returns true when running in browser', () => {
+      expect(isClientSide()).toBe(true)
+    })
+  })
+
+  describe('server', () => {
+
+    const g: any = global
+    const window = g.window
+    beforeEach(() => {
+      delete g.window
+    })
+
+    afterEach(() => {
+      g.window = window
+    })
+    it('returns false when running on server', () => {
+      expect(isClientSide()).toBe(false)
+    })
+  })
+
+})
diff --git a/packages/client/src/renderer/isClientSide.ts b/packages/client/src/renderer/isClientSide.ts
new file mode 100644
index 0000000..d907866
--- /dev/null
+++ b/packages/client/src/renderer/isClientSide.ts
@@ -0,0 +1,5 @@
+export function isClientSide() {
+  return typeof window !== 'undefined' &&
+    typeof window.document !== 'undefined' &&
+    typeof window.document.createElement === 'function'
+}