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

MongoDB query language for in-memory objects

import { computeValue } from "../../../core/_internal";
import { assert, isArray, isInteger, isNil } from "../../../util";
import { errExpectArray, errExpectNumber, INT_OPTS } from "../_internal";
const OP = "$arrayElemAt";
const $arrayElemAt = (obj, expr, options) => {
  assert(isArray(expr) && expr.length === 2, `${OP} expects array(2)`);
  const args = computeValue(obj, expr, null, options);
  if (args.some(isNil)) return null;
  const foe = options.failOnError;
  const [arr, index] = args;
  if (!isArray(arr)) return errExpectArray(foe, `${OP} arg1 <array>`);
  if (!isInteger(index))
    return errExpectNumber(foe, `${OP} arg2 <index>`, INT_OPTS.int);
  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
};