optimizations (#1578)

src/use-swr.ts

@@ -3,7 +3,7 @@ import { defaultConfig } from './utils/config'
 import { SWRGlobalState, GlobalState } from './utils/global-state'
 import { IS_SERVER, rAF, useIsomorphicLayoutEffect } from './utils/env'
 import { serialize } from './utils/serialize'
-import { isUndefined, UNDEFINED, mergeObjects } from './utils/helper'
+import { isUndefined, UNDEFINED, OBJECT, mergeObjects } from './utils/helper'
 import ConfigProvider from './utils/config-context'
 import { useStateWithDeps } from './utils/state'
 import { withArgs } from './utils/resolve-args'
@@ -501,7 +501,7 @@ export const useSWRHandler = <Data = any, Error = any>(
   } as SWRResponse<Data, Error>
 }
 
-export const SWRConfig = Object.defineProperty(ConfigProvider, 'default', {
+export const SWRConfig = OBJECT.defineProperty(ConfigProvider, 'default', {
   value: defaultConfig
 }) as typeof ConfigProvider & {
   default: FullConfiguration

src/utils/broadcast-state.ts

@@ -19,13 +19,11 @@ export const broadcastState: Broadcaster = (
     CONCURRENT_PROMISES_TS
   ] = SWRGlobalState.get(cache) as GlobalState
   const revalidators = EVENT_REVALIDATORS[key]
-  const updaters = STATE_UPDATERS[key]
+  const updaters = STATE_UPDATERS[key] || []
 
   // Always update states of all hooks.
-  if (updaters) {
-    for (let i = 0; i < updaters.length; ++i) {
-      updaters[i](data, error, isValidating)
-    }
+  for (let i = 0; i < updaters.length; ++i) {
+    updaters[i](data, error, isValidating)
   }
 
   // If we also need to revalidate, only do it for the first hook.

src/utils/config-context.ts

@@ -2,7 +2,7 @@ import { createContext, createElement, useContext, useState, FC } from 'react'
 import { cache as defaultCache } from './config'
 import { initCache } from './cache'
 import { mergeConfigs } from './merge-config'
-import { UNDEFINED } from './helper'
+import { UNDEFINED, mergeObjects } from './helper'
 import { useIsomorphicLayoutEffect } from './env'
 import {
   SWRConfiguration,
@@ -18,7 +18,9 @@ const SWRConfig: FC<{
     Partial<ProviderConfiguration> & {
       provider?: (cache: Readonly<Cache>) => Cache
     }
-}> = ({ children, value }) => {
+}> = props => {
+  const { value } = props
+
   // Extend parent context values and middleware.
   const extendedConfig = mergeConfigs(useContext(SWRConfigContext), value)
 
@@ -46,8 +48,9 @@ const SWRConfig: FC<{
 
   return createElement(
     SWRConfigContext.Provider,
-    { value: extendedConfig },
-    children
+    mergeObjects(props, {
+      value: extendedConfig
+    })
   )
 }
 

src/utils/hash.ts

@@ -1,4 +1,4 @@
-import { isUndefined } from './helper'
+import { OBJECT, isUndefined } from './helper'
 
 // use WeakMap to store the object->key mapping
 // so the objects can be garbage collected.
@@ -25,7 +25,7 @@ export const stableHash = (arg: any): string => {
   let result: any
   let index: any
 
-  if (Object(arg) === arg && !isDate && constructor != RegExp) {
+  if (OBJECT(arg) === arg && !isDate && constructor != RegExp) {
     // Object/function, not null/date/regexp. Use WeakMap to store the id first.
     // If it's already hashed, directly return the result.
     result = table.get(arg)
@@ -45,10 +45,10 @@ export const stableHash = (arg: any): string => {
       }
       table.set(arg, result)
     }
-    if (constructor == Object) {
+    if (constructor == OBJECT) {
       // Object, sort keys.
       result = '#'
-      const keys = Object.keys(arg).sort()
+      const keys = OBJECT.keys(arg).sort()
       while (!isUndefined((index = keys.pop() as string))) {
         if (!isUndefined(arg[index])) {
           result += index + ':' + stableHash(arg[index]) + ','

src/utils/helper.ts

@@ -6,9 +6,11 @@ export const noop = () => {}
 // prettier-ignore
 export const UNDEFINED: undefined = (/*#__NOINLINE__*/ noop()) as undefined
 
+export const OBJECT = Object
+
 export const isUndefined = (v: any): v is undefined => v === UNDEFINED
 export const isFunction = (v: any): v is Function => typeof v == 'function'
-export const mergeObjects = (a: any, b: any) => Object.assign({}, a, b)
+export const mergeObjects = (a: any, b: any) => OBJECT.assign({}, a, b)
 
 const STR_UNDEFINED = 'undefined'
 export const hasWindow = typeof window != STR_UNDEFINED

src/utils/resolve-args.ts

@@ -1,24 +1,17 @@
-import { useContext } from 'react'
-
-import { defaultConfig } from './config'
-import { SWRConfigContext } from './config-context'
 import { mergeConfigs } from './merge-config'
 import { normalize } from './normalize-args'
-import { mergeObjects } from './helper'
+import { useSWRConfig } from './use-swr-config'
 
 // It's tricky to pass generic types as parameters, so we just directly override
 // the types here.
 export const withArgs = <SWRType>(hook: any) => {
   return (((...args: any) => {
+    // Get the default and inherited configuration.
+    const fallbackConfig = useSWRConfig()
+
     // Normalize arguments.
     const [key, fn, _config] = normalize<any, any>(args)
 
-    // Get the default and inherited configuration.
-    const fallbackConfig = mergeObjects(
-      defaultConfig,
-      useContext(SWRConfigContext)
-    )
-
     // Merge configurations.
     const config = mergeConfigs(fallbackConfig, _config)