JavaScript Language Patterns
Priority: P0 (CRITICAL)
Modern JavaScript standards for clean, maintainable code.
Implementation Guidelines
- •Variables:
constdefault.letif needed. Novar. - •Functions: Arrows for callbacks. Declarations for top-level.
- •Async:
async/await+try/catch. - •Objects: Destructuring, Spread
..., Optional Chain?., Nullish??. - •Strings: Template literals
${}. - •Arrays:
map,filter,reduce. No loops. - •Modules: ESM
import/export. Export only what is necessary. - •Classes: Use
#privatefields for true privacy.
Anti-Patterns
- •No
var: Block scope only. - •No
==: Strict===. - •No
new Object(): Use literals{}. - •No Callbacks: Promisify everything.
- •No Mutation: Immutability first.
Code
javascript
// Modern Syntax
const [x, ...rest] = items;
const name = user?.profile?.name ?? 'Guest';
// Async
async function getUser(id) {
try {
const res = await fetch(`/api/${id}`);
return res.json();
} catch (err) {
console.error(err);
throw err;
}
}
// Class + Private
class Service {
#key;
constructor(k) {
this.#key = k;
}
}
Reference & Examples
For advanced patterns and functional programming: See references/REFERENCE.md.
Related Topics
best-practices | tooling