Tree shaking example

abc.js

import { d, e, f } from "./def.js";

// a is used
export const a = d + " is part of a";
// b is unused
export const b = e + " is part of b";
// c is unused
export const c = f + " is part of c";

def.js

export const d = "d";
export const e = "e";
export const f = "f";

/*
 * d, e and f will all be marked as "used" because they are imported into abc.js
 * but e and f will never be used because the variables that rely on them are unused.
 * Assuming I am able to detect this situation (it's a specific kind of module),
 * is it possible to tell webpack that these exports are actually unused?
 */

index.js

import { a } from "./abc.js";

document.write(a);