Typescript generic "make a compare function" function that takes a lambda, expected to return the property to compare (normally).

makeCompareFunction.ts

/* Create a function used with `sort()` to sort arrays of objects
 * for example:
 *   const sortByLastName = makeCompareFunction<Person>(p => p.lastName);
 *   people.sort(sortByLastName);
 */
export function makeCompareFunction<T>(lambda: (obj: T) => string | number) {
  return (a: T, b: T): number => {
    const _a = lambda(a);
    const _b = lambda(b);
    if (_a < _b) {
      return -1;
    }
    if (_a > _b) {
      return 1;
    }
    return 0;
  };
}