Fueling Curiosity, One Insight at a Time

So if we want to mock the useRouter hook in NextJs, we can use vi for it.
The "vi" library's function vi.mock allows us to simulate the behaviour of the useRouter hook. The mock function returns an object that mimics the Router object's properties and methods.

vi.mock("next/router", () => ({
    useRouter: () => ({
      replace: vi.fn(),
    }),
  }));

replace: a mock function that simulates the behavior of the replace method of the Router object.
If we do not use it, the test might fail and we get the following error.
Error: NextRouter was not mounted.

userEvent is considered to be a more reliable and secure way of triggering events in the browser because user events are events that are triggered by a user's interaction with the webpage and reflect the actual user behavior on the page.
However, fireEvent is a means of programmatically activating an event (dispatching DOM events) in the browser, which can be less dependable.

Reference: https://testing-library.com/docs/user-event/intro/#difference-to-fireevent

userEvent is more reliable and easy to use rather than fireEvent.
userEvent provides wide range of browser events options and it is like interacting with events same as we interact in browser

We can easily browse s3 folder locally by using this https://github.com/awslabs/mountpoint-s3 tool

Postgres query uses || as string concatenation instead of +

We can type JSON into https://app.quicktype.io/ and it generates TypeScript type.

Can be helpful in defining types for api response (usually while integrating third party apis where large amounts of data is returned).

you can whitelist IPs and ranges in nginx. When we have separate virtual hosts these are saved in /etc/nginx/sites-enabled. The rules look like allow xx.xx.xx.xx/range(32); and deny all;. Further we can make sure nginx passes some headers to the app using the rules proxy_set_header Host $http_host;.

We can use the following where clause to filter users based on their age using a Postgres query
(CURRENT_DATE - INTERVAL '18 years')::date < TO_DATE(T3.DATE_OF_BIRTH, 'YYYY-MM-DD')

As a Next.js app can be executed on both the server and the client side. When the app is rendered on the server, there is no access to the browser-specific features like localStorage, as it is a feature of the client-side browser environment.

So let's say, if we try to use localStorage in a Next.js app, we may encounter issues when the app is being server-side rendered.

To avoid this problem, we can check if localStorage is available before using it in our Next.js app.

if(typeoflocalStorage!== 'undefined') { 
// Use localStorage here
} 

This way, our app will only use localStorage when it is available, and avoid errors when it is not.

Bring the suspended server to foreground using fg command. Say the server is running and we want to install a package

1. Ctrl+Z
2. yarn add jsonwebtoken
3. fg

And the server resumes