TypeScript Skill
Rules
Note that these are not hard-and-fast rules. If there's a good reason not to apply a rule, don't apply it.
Alphabetical Order
Maintain alphabetical order for better readability and consistency:
- Function parameters - Order by parameter name
- Object literal fields - Sort by key name
- Type definitions - Arrange fields alphabetically
- Class properties - Order by property name
Example (type definitions):
// bad
type User = {
name: string;
age: number;
email: string;
};
// good
type User = {
age: number;
email: string;
name: string;
};Biome
Use BiomeJS for linting and formatting JavaScript and TypeScript code. Look for a biome.jsonc file.
Exception: project already uses ESLint and Prettier.
dayjs for date and time calculations
Use the dayjs library for date calculations. Avoid using the native JavaScript Date object.
Example:
import dayjs from "dayjs";
const now = dayjs();
const tomorrow = now.add(1, "day");No any type
Never use the any type.
No nested ternary operators
Avoid nested ternary operators. Use if/else statements or early returns instead.
Example:
// bad
const result = a ? b : c ? d : e;
// good
if (a) {
return b;
}
if (c) {
return d;
}
return e;Never return a value in forEach callbacks
Example:
[].forEach(() => {
return 1; // bad
});
[].forEach(() => {
// good
});Another example:
[].forEach((item) => console.log(item)); // bad
[].forEach((item) => {
console.log(item); // good
});Prefer type instead of interface
Use type instead of interface for declaring types.
Comment Dividers
Use centered comment dividers for major section breaks:
Format (80 chars total):
// -------------------------------------------------------------------------- //
// TITLE //
// -------------------------------------------------------------------------- //Rules:
- Total width: 80 characters
- Title: UPPERCASE, centered with spaces
- Border line: dashes
-filling the space between//and//
When to use:
- Major logical sections (imports, types, constants, main logic, exports)
- Separating distinct feature areas
- NOT for every function or small grouping
Example:
// -------------------------------------------------------------------------- //
// IMPORTS //
// -------------------------------------------------------------------------- //
import { Effect } from "effect";
// -------------------------------------------------------------------------- //
// TYPES //
// -------------------------------------------------------------------------- //
type Config = {
name: string;
};