slice() - A generator function that allows you to get a slice of the values within the given array-like object.

slice.js

/**
 * Generator function allowing you to get a slice of the values within the given
 * array-like object.
 * @template T
 * @param {T[]} list
 *   The array or array-like object that will be iterated over.
 * @param {Object} options
 *   Optional.  The options to change the order of the returned values.
 * @param {number=} options.start
 *   The starting index within `list`.  If this is a negative value the starting
 *   index will be calculated starting from the end of `list`.
 * @param {number=} options.stop
 *   The stopping index within `list`.  If this is a negative value the starting
 *   index will be calculated stopping from the end of `list`.
 * @param {number=} options.step
 *   The amount by which to increment the index between each value to be
 *   returned within `list`.  If this is a negative value the values will be
 *   returned in reverse order.
 * @return {Generator<{value: T, index: number, list: T[]}>}
 * @example
 *   // Get all divs in order.
 *   for (const {index, value} of slice(document.querySelectorAll('div'))) {
 *     console.log(index, value);
 *   }
 * @example
 *   // Get all divs in reverse order.
 *   const iter = slice(document.querySelectorAll('div'), {step: -1});
 *   for (const {index, value} of iter) {
 *     console.log(index, value);
 *   }
 */
function* slice(list, options) {
    let {start, stop, step} = Object(options);

    // Make a shallow copy of list as an array.
    const array = Array.from(list);

    // Ensuring that step, start and stop are correctly defined.
    step ||= 1;
    const increasing = step > 0;
    if (increasing) {
        if (start == null) start = 0;
        if (stop == null) stop = -1;
    }
    else {
        if (start == null) start = -1;
        if (stop == null) stop = 0;
    }
    if (start < 0) start = array.length >= -start ? array.length + start : 0;
    if (stop < 0) stop = array.length >= -stop ? array.length + stop : 0;

    for (let index = start; increasing ? index <= stop : (index >= stop); index += step) {
        yield {value: array[index], index, list};
    }
}