mingo/dist/esm/operators/expression/array/arrayElemAt.js

MongoDB query language for in-memory objects

import { computeValue } from "../../../core";
import { assert, isNil } from "../../../util";
const $arrayElemAt = (obj, expr, options) => {
  const args = computeValue(obj, expr, null, options);
  assert(
    args instanceof Array && args.length === 2,
    "$arrayElemAt expression must resolve to array(2)"
  );
  if (args.some(isNil))
    return null;
  const index = args[1];
  const arr = args[0];
  if (index < 0 && Math.abs(index) <= arr.length) {
    return arr[(index + arr.length) % arr.length];
  } else if (index >= 0 && index < arr.length) {
    return arr[index];
  }
  return void 0;
};
export {
  $arrayElemAt
};