perf: use typeof window to detect browser (#810)

src/lib/stylesheet.js

@@ -10,11 +10,7 @@ const isProd =
 const isString = o => Object.prototype.toString.call(o) === '[object String]'
 
 export default class StyleSheet {
-  constructor({
-    name = 'stylesheet',
-    optimizeForSpeed = isProd,
-    isBrowser = typeof window !== 'undefined'
-  } = {}) {
+  constructor({ name = 'stylesheet', optimizeForSpeed = isProd } = {}) {
     invariant(isString(name), '`name` must be a string')
     this._name = name
     this._deletedRulePlaceholder = `#${name}-deleted-rule____{}`
@@ -24,15 +20,14 @@ export default class StyleSheet {
       '`optimizeForSpeed` must be a boolean'
     )
     this._optimizeForSpeed = optimizeForSpeed
-    this._isBrowser = isBrowser
-
     this._serverSheet = undefined
     this._tags = []
     this._injected = false
     this._rulesCount = 0
 
     const node =
-      this._isBrowser && document.querySelector('meta[property="csp-nonce"]')
+      typeof window !== 'undefined' &&
+      document.querySelector('meta[property="csp-nonce"]')
     this._nonce = node ? node.getAttribute('content') : null
   }
 
@@ -58,7 +53,7 @@ export default class StyleSheet {
   inject() {
     invariant(!this._injected, 'sheet already injected')
     this._injected = true
-    if (this._isBrowser && this._optimizeForSpeed) {
+    if (typeof window !== 'undefined' && this._optimizeForSpeed) {
       this._tags[0] = this.makeStyleTag(this._name)
       this._optimizeForSpeed = 'insertRule' in this.getSheet()
       if (!this._optimizeForSpeed) {
@@ -112,7 +107,7 @@ export default class StyleSheet {
   insertRule(rule, index) {
     invariant(isString(rule), '`insertRule` accepts only strings')
 
-    if (!this._isBrowser) {
+    if (typeof window === 'undefined') {
       if (typeof index !== 'number') {
         index = this._serverSheet.cssRules.length
       }
@@ -149,8 +144,9 @@ export default class StyleSheet {
   }
 
   replaceRule(index, rule) {
-    if (this._optimizeForSpeed || !this._isBrowser) {
-      const sheet = this._isBrowser ? this.getSheet() : this._serverSheet
+    if (this._optimizeForSpeed || typeof window === 'undefined') {
+      const sheet =
+        typeof window !== 'undefined' ? this.getSheet() : this._serverSheet
       if (!rule.trim()) {
         rule = this._deletedRulePlaceholder
       }
@@ -184,7 +180,7 @@ export default class StyleSheet {
   }
 
   deleteRule(index) {
-    if (!this._isBrowser) {
+    if (typeof window === 'undefined') {
       this._serverSheet.deleteRule(index)
       return
     }
@@ -202,7 +198,7 @@ export default class StyleSheet {
   flush() {
     this._injected = false
     this._rulesCount = 0
-    if (this._isBrowser) {
+    if (typeof window !== 'undefined') {
       this._tags.forEach(tag => tag && tag.parentNode.removeChild(tag))
       this._tags = []
     } else {
@@ -212,7 +208,7 @@ export default class StyleSheet {
   }
 
   cssRules() {
-    if (!this._isBrowser) {
+    if (typeof window === 'undefined') {
       return this._serverSheet.cssRules
     }
 

src/stylesheet-registry.js

@@ -19,11 +19,7 @@ function mapRulesToStyle(cssRules, options = {}) {
   })
 }
 export class StyleSheetRegistry {
-  constructor({
-    styleSheet = null,
-    optimizeForSpeed = false,
-    isBrowser = typeof window !== 'undefined'
-  } = {}) {
+  constructor({ styleSheet = null, optimizeForSpeed = false } = {}) {
     this._sheet =
       styleSheet ||
       new DefaultStyleSheet({
@@ -37,8 +33,6 @@ export class StyleSheetRegistry {
       this._optimizeForSpeed = this._sheet.isOptimizeForSpeed()
     }
 
-    this._isBrowser = isBrowser
-
     this._fromServer = undefined
     this._indices = {}
     this._instancesCounts = {}
@@ -51,7 +45,7 @@ export class StyleSheetRegistry {
       this._optimizeForSpeed = this._sheet.isOptimizeForSpeed()
     }
 
-    if (this._isBrowser && !this._fromServer) {
+    if (typeof window !== 'undefined' && !this._fromServer) {
       this._fromServer = this.selectFromServer()
       this._instancesCounts = Object.keys(this._fromServer).reduce(
         (acc, tagName) => {

test/helpers/with-mock.js

@@ -11,9 +11,9 @@ export default function withMock(mockFn, testFn) {
 }
 
 export function withMockDocument(t) {
-  const originalDocument = global.document
+  const originalDocument = globalThis.document
   // We need to stub a document in order to simulate the meta tag
-  global.document = {
+  globalThis.document = {
     querySelector(query) {
       t.is(query, 'meta[property="csp-nonce"]')
       return {
@@ -26,6 +26,6 @@ export function withMockDocument(t) {
   }
 
   return () => {
-    global.document = originalDocument
+    globalThis.document = originalDocument
   }
 }

test/stylesheet-registry.js

@@ -7,7 +7,7 @@ import makeSheet, { invalidRules } from './stylesheet'
 import withMock, { withMockDocument } from './helpers/with-mock'
 import { computeId, computeSelector } from '../src/lib/hash'
 
-function makeRegistry(options = { optimizeForSpeed: true, isBrowser: true }) {
+function makeRegistry(options = { optimizeForSpeed: true }) {
   const registry = new StyleSheetRegistry({
     styleSheet: makeSheet(options),
     ...options
@@ -32,7 +32,12 @@ test(
     ]
 
     options.forEach(options => {
+      if (options.isBrowser) {
+        globalThis.window = globalThis
+      }
+
       const registry = makeRegistry(options)
+
       registry.add({
         id: '123',
         children: options.optimizeForSpeed ? [cssRule] : cssRule
@@ -68,13 +73,19 @@ test(
           ['jsx-456', 'div { color: red }p { color: red }']
         ])
       }
+
+      if (options.isBrowser) {
+        delete globalThis.window
+      }
     })
   })
 )
 
 test(
   'add - filters out invalid rules (index `-1`)',
   withMock(withMockDocument, t => {
+    globalThis.window = globalThis
+
     const registry = makeRegistry()
 
     // Insert a valid rule
@@ -90,12 +101,16 @@ test(
       ['jsx-123', 'div { color: red }'],
       ['jsx-678', 'div { color: red }']
     ])
+
+    delete globalThis.window
   })
 )
 
 test(
   'it does not throw when inserting an invalid rule',
   withMock(withMockDocument, t => {
+    globalThis.window = globalThis
+
     const registry = makeRegistry()
 
     // Insert a valid rule
@@ -107,11 +122,13 @@ test(
     })
 
     t.deepEqual(registry.cssRules(), [['jsx-123', 'div { color: red }']])
+
+    delete globalThis.window
   })
 )
 
 test('add - sanitizes dynamic CSS on the server', t => {
-  const registry = makeRegistry({ optimizeForSpeed: false, isBrowser: false })
+  const registry = makeRegistry({ optimizeForSpeed: false })
 
   registry.add({
     id: '123',
@@ -130,9 +147,9 @@ test('add - sanitizes dynamic CSS on the server', t => {
 })
 
 test('add - nonce is properly fetched from meta tag', t => {
-  const originalDocument = global.document
+  const originalDocument = globalThis.document
   // We need to stub a document in order to simulate the meta tag
-  global.document = {
+  globalThis.document = {
     querySelector(query) {
       t.is(query, 'meta[property="csp-nonce"]')
       return {
@@ -144,12 +161,16 @@ test('add - nonce is properly fetched from meta tag', t => {
     }
   }
 
+  globalThis.window = globalThis
+
   const registry = makeRegistry()
   registry.add({ id: '123', children: [cssRule] })
 
   t.is(registry._sheet._nonce, 'test-nonce')
 
-  global.document = originalDocument
+  globalThis.document = originalDocument
+
+  delete globalThis.window
 })
 
 // registry.remove
@@ -165,6 +186,10 @@ test(
     ]
 
     options.forEach(options => {
+      if (options.isBrowser) {
+        globalThis.window = globalThis
+      }
+
       const registry = makeRegistry(options)
       registry.add({
         id: '123',
@@ -192,6 +217,10 @@ test(
       registry.remove({ id: '345' })
       // now the registry should be empty
       t.deepEqual(registry.cssRules(), [])
+
+      if (options.isBrowser) {
+        delete globalThis.window
+      }
     })
   })
 )
@@ -209,6 +238,10 @@ test(
     ]
 
     options.forEach(options => {
+      if (options.isBrowser) {
+        globalThis.window = globalThis
+      }
+
       const registry = makeRegistry(options)
       registry.add({
         id: '123',
@@ -246,6 +279,10 @@ test(
       )
       // 123 replaced with 345
       t.deepEqual(registry.cssRules(), [['jsx-345', cssRuleAlt]])
+
+      if (options.isBrowser) {
+        delete globalThis.window
+      }
     })
   })
 )