Like a Set, but provides the index of the `key` in the backing array
npm install @jridgewell/set-array> Like a Set, but provides the index of the key in the backing array
This is designed to allow synchronizing a second array with the contents of the backing array, like
how in a sourcemap sourcesContent[i] is the source content associated with source[i], and there
are never duplicates.
``sh`
npm install @jridgewell/set-array
`js
import { SetArray, get, put, pop } from '@jridgewell/set-array';
const sa = new SetArray();
let index = put(sa, 'first');
assert.strictEqual(index, 0);
index = put(sa, 'second');
assert.strictEqual(index, 1);
assert.deepEqual(sa.array, [ 'first', 'second' ]);
index = get(sa, 'first');
assert.strictEqual(index, 0);
pop(sa);
index = get(sa, 'second');
assert.strictEqual(index, undefined);
assert.deepEqual(sa.array, [ 'first' ]);
``