Sort an object in place or by copy (TypeScript/JavaScript)

sortObject.ts

// JavaScript versions at the bottom


// ----- TypeScript: -----

type ObjectCompareFn = (a: string, b: string) => number;

/** Sorts an object in place */
export function sortObject<T extends object>(obj: T, compareFn?: ObjectCompareFn): T {
  Object.keys(obj).sort(compareFn).forEach(key => {
    const value = obj[key];
    delete obj[key];
    obj[key] = value;
  });
  return obj;
}

/** Returns a sorted copy of an object */
export function sortedObject<T extends object>(obj: T, compareFn?: ObjectCompareFn): T {
  return Object.keys(obj).sort(compareFn).reduce((copy, key) => {
    copy[key] = obj[key];
    return copy;
  }, {}) as T;
}

  
// ----- JavaScript: -----


/**
 * Sorts an object in place
 * @param {T} obj
 * @param {undefined(string, string) => number} compareFn
 * @returns {T} reference to obj
 */
function sortObject(obj, compareFn) {
  Object.keys(obj).sort(compareFn).forEach(key => {
    const value = obj[key];
    delete obj[key];
    obj[key] = value;
  });
  return obj;
}

/**
 * Returns a sorted copy of an object
 * @param {T} obj
 * @param {undefined | (string, string) => number} compareFn
 * @returns {T}
 */
function sortedObject(obj, compareFn) {
  return Object.keys(obj).sort(compareFn).reduce((copy, key) => {
    copy[key] = obj[key];
    return copy;
  }, {});
}