index.js

// @ts-check

import {
  cons,
  car,
  cdr,
  toString as toStr,
} from '@hexlet/pairs';

/**
 * Make a point
 * @example
 * const point = makePoint(4, 5);
 */
export const makePoint = (x, y) => cons(x, y);

/**
 * Get X
 * @example
 * const point = makePoint(4, 5);
 * getX(point); // 4
 */
export const getX = (point) => car(point);

/**
 * Get Y
 * @example
 * const point = makePoint(8, -2);
 * getY(point); // -2
 */
export const getY = (point) => cdr(point);

/**
 * Convert point to string
 * @example
 * const point = makePoint(0, 10);
 * toString(point); // (0, 10)
 */
export const toString = (point) => toStr(point);

/**
 * Determine quadrant for given point
 * @example
 * quadrant(makePoint(5, 0)); // null
 * quadrant(makePoint(1, 5)); // 1
 * quadrant(makePoint(-3, 10)); // 2
 */
export const quadrant = (point) => {
  const x = getX(point);
  const y = getY(point);

  if (x > 0 && y > 0) {
    return 1;
  }
  if (x < 0 && y > 0) {
    return 2;
  }
  if (x < 0 && y < 0) {
    return 3;
  }
  if (x > 0 && y < 0) {
    return 4;
  }

  return null;
};