JQ.ES6.getNumericRange.js

/**
 * Gives a numeric range
 * 
 * @param {number} start - initial number
 * @param {number} stop - final number
 * @param {number} step - increment value
 * @returns {Array} numeric range between start and stop by increments of step
 * 
 * Example: numericRange(-2, 2, 1) = numericRange(-2, 2) => [-2, -1, 0, 1, 2]
 */
function getNumericRange(start, stop, step = 1) {
  return Array.from({ length: Math.ceil((stop + 1 - start) / step) }, (_, i) => start + i * step);
}

/**
 * TESTS
**/
describe('getNumericRange', () => {
  it('should return array of 5 elements from -2 to 2', () => {
    const newArray = helpers.getNumericRange(-2, 2);
    const expectedArray = [-2, -1, 0, 1, 2];
    expect(newArray).to.deep.equal(expectedArray);
  });
  it('should return array of 5 elements from -4 to 4 with step 2', () => {
    const newArray = helpers.getNumericRange(-4, 4, 2);
    const expectedArray = [-4, -2, 0, 2, 4];
    expect(newArray).to.deep.equal(expectedArray);
  });
  it('should return array of 10 elements from 0 to 10', () => {
    const newArray = helpers.getNumericRange(0, 10, 1);
    const expectedArray = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
    expect(newArray).to.deep.equal(expectedArray);
  });
});