Utility functions for converting between coordinate objects and string keys. This module provides functions to convert a coordinate object with x and y properties into a string key, and to convert a string key back into a coordinate object. The coordinate format is "x,y", where x and y are numbers. The functions are useful for storing and retrieving coordinates in a hash map or similar data structure.

// Example usage:
const coord = { x: 10, y: 20 };
const key = coord2Key(coord); // "10,20"
const newCoord = key2Coord(key); // { x: 10, y: 20 }
console.log(newCoord); // { x: 10, y: 20 }