Next. js_Next.js: run the code server-side or client-side only in Next.js

next. js
In your page components, you can execute code only in the server-side or on the client-side, but checking the window property.
This property is only existing inside the browser, so you can check    


if (typeof window === 'undefined') {

}

and add the server-side code in that block. 

Similarly, you can execute client-side code only by checking   


if (typeof window !== 'undefined') {

}

Alternatively, the following can be used to determine  _document.tsx  just run on the server

if (!process.browser) { 

console.log('This is running on the server.');

 } else {

 console.log('This is running in the browser.');

 }