Use consistent capitalization

Capitalization tells you a lot about your variables, functions, etc. These rules are subjective, so your team can choose whatever they want. The point is, no matter what you all choose, just be consistent.

Bad:

const DAYS_IN_WEEK = 7;
const daysInMonth = 30;

const songs = ['Back In Black', 'Stairway to Heaven', 'Hey Jude'];
const Artists = ['ACDC', 'Led Zeppelin', 'The Beatles'];

function eraseDatabase() {}
function restore_database() {}

type animal = {
  /* ... */
};
type Container = {
  /* ... */
};

Good:

const DAYS_IN_WEEK = 7;
const DAYS_IN_MONTH = 30;

const SONGS = ['Back In Black', 'Stairway to Heaven', 'Hey Jude'];
const ARTISTS = ['ACDC', 'Led Zeppelin', 'The Beatles'];

const discography = getArtistDiscography('ACDC');
const beatlesSongs = SONGS.filter((song) => isBeatlesSong(song));

function eraseDatabase() {}
function restoreDatabase() {}

type Animal = {
  /* ... */
};
type Container = {
  /* ... */
};

Prefer using PascalCase for class, interface, type and namespace names.

Prefer using camelCase for variables, functions and class members.

Prefer using capitalized SNAKE_CASE for constants.