Designates one primary value a JavaScript module makes available through its default property. A module can have one default export alongside multiple named exports. section 11.1.2
Exporting a utility
A module can expose one function as its default export and another as a named export: `export default function sayMessage(...) { ... }` and `export function sayHi(...) { ... }`. Dynamic imports access them as `module.default` and `module.sayHi`, or through destructuring. section 11.1.2 section 11.1.4
Lazy-loading a component
React.lazy expects the promise from a dynamic import to resolve to a module whose default export is a component: `const LazyCalendar = lazy(() => import("./Calendar.js"));`. A calendar can therefore load when the user first clicks Show Calendar. section 11.2.1
