For the async search option, you should consider using promises/async-await instead of callbacks.

Instead of:

index.search("John", function(result){ 
  // array of results
});

Do:

index.search("John").then(function(result){ 
  // array of results
});

Or:

const results = await index.search("John");

More on reddit.com

_ is often used as a throwaway variable. In other words, just ignore it. It's the same thing as this: [...Array(5)].map((unused, x) => x++); Also, you don't need to x++, just x would do. More on reddit.com

but I typically don't need the unsorted one anymore More on reddit.com

When dealing with large arrays (10^6 > elements), concatenating them can be very memory-consuming. This solution joins arrays logically, turning a list of arrays into an iterable, with additional "length" and "at" access. See also the source repo: https://github.com/vitaly-t/chain-arrays . const a = [1, 2]; const b = [3, 4]; const c = [5, 6]; for (const value of chainArrays(a, b, c)) { console.log(value); //=> 1, 2, 3, 4, 5, 6 } for (const value of chainArraysReverse(a, b, c)) { console.log(value); //=> 6, 5, 4, 3, 2, 1 } How good is performance of such logical iteration? Here's a simple test: import {chainArrays} from './chain-arrays'; const r = 10_000_000; const a = Array(r).fill(1); const b = Array(r).fill(2); const c = Array(r).fill(3); const d = Array(r).fill(4); const e = Array(r).fill(5); const start = Date.now(); let sum = 0; for (const i of chainArrays(a, b, c, d, e)) { sum += i; } console.log(`${Date.now() - start}ms`); //=> ~100ms Above, we iterate over 5 arrays, with 10 mln elements each, within 100ms. For comparison, using the spread syntax for the same: let sum = 0; for (const i of [...a, ...b, ...c, ...d, ...e]) { sum += i; } console.log(`${Date.now() - start}ms`); //=> ~1175ms That took 11.7 times longer, while also consuming tremendously more memory. The same iteration via index is roughly 2 times slower, as it needs to calculate the source array index every time you use "at" function: let sum = 0; const chain = chainArrays(a, b, c, d, e); for (let t = 0; t < chain.length; t++) { sum += chain.at(t)!; } console.log(`${Date.now() - start}ms`); //=> ~213ms More on reddit.com