refactor: Use initImmediate in SSR

__tests__/config/create-config.test.ts

@@ -48,6 +48,7 @@ describe('create configuration in non-production environment', () => {
     })
 
     it('creates default non-production configuration', () => {
+      isServer.mockReturnValue(true)
       const config = createConfig({})
 
       expect(config.defaultLanguage).toEqual('en')
@@ -72,6 +73,8 @@ describe('create configuration in non-production environment', () => {
 
       expect(config.react.wait).toEqual(true)
 
+      expect(config.initImmediate).toEqual(false)
+
       expect(config.preload).toEqual(['en'])
 
       expect(config.ns).toEqual(['common', 'file1', 'file2'])
@@ -161,6 +164,8 @@ describe('create configuration in non-production environment', () => {
 
       expect(config.react.wait).toEqual(true)
 
+      expect(config.initImmediate).toEqual(true)
+
       expect(config.preload).toBeUndefined()
 
       expect(config.ns).toEqual(['common'])

__tests__/middlewares/next-i18next-middleware.test.ts

@@ -23,6 +23,7 @@ jest.mock('../../src/utils', () => ({
   subpathFromLng: jest.fn(),
   lngFromReq: jest.fn(),
   removeSubpath: jest.fn(),
+  isServer: jest.fn(),
 }))
 
 describe('next-18next middleware', () => {

src/config/default-config.ts

@@ -1,3 +1,5 @@
+import { isServer } from '../utils'
+
 const DEFAULT_LANGUAGE = 'en'
 const OTHER_LANGUAGES = []
 const DEFAULT_NAMESPACE = 'common'
@@ -35,6 +37,9 @@ const config = {
   },
   strictMode: true,
   errorStackTraceLimit: 0,
+  get initImmediate() {
+    return !isServer()
+  }
 }
 
 export default config

tsconfig.json

@@ -3,6 +3,7 @@
     "esModuleInterop": true,
     "noEmit": true,
     "lib": ["esnext", "dom"],
+    "target": "es5",
     "jsx": "react"
   },
   "include": [