JavaScript Ranges

RangeArray.js

/**
 * A function to generate array ranges (zero-indexed)
 * @param {number} from
 * @param {number} to
 */
export function RangeArray(from, to) {
  var r = [];
  
  if (typeof from !== 'number' && typeof to !== 'number') {
    throw new Error('RangeArray expects a number');
  }
  
  r = [...Array(to || from).keys()];
  
  return to ? r.slice(from) : r;
}

// new RangeArray(5) => [0,1,2,3,4]
// new RangeArray(5, 10) => [5,6,7,8,9,10,11,12,13,14]