Tests
- Falsy:
!!value or Boolean(value)
- NaN:
Number.isNaN(value)
- Null or Undefined:
value == null (double-equals)
- Null only:
value === null
- Undefined only:
typeof(value) == 'undefined'
Modules
export function foo() {}
export const bar = () => {};
const baz = () => {};
export default baz;
export default function baz() {};
// INVALID
export default const qux = () => {};
Regex
if (/regex/.test(string)) {
}
Utilities
function range(start, end) {
return Array.from({ length: end - start + 1 }, (_, i) => start + i)
}