I am a newbie js "developer" and for practice, I created a tiny (8 methods) JavaScript library. I need you to give me feedback "should I keep expanding my library or switch to something else" and how do I improve the code quality?

full code:

function isObject(val) {
      if (val === null) { return false;}
      return ( (typeof val === 'function') || (typeof val === 'object') );
function isDate(value) {
      switch (typeof value) {
          case 'number':
              return true;
          case 'string':
              return !isNaN(Date.parse(value));
          case 'object':
              if (value instanceof Date) {
                  return !isNaN(value.getTime());
              return false;
function isEmptyOrOnlySpacesString(str) {
      return (!str || /^\s*$/.test(str));
function getTimeZone() {
      return Intl.DateTimeFormat().resolvedOptions().timeZone;
function doesObjectHaveEmptyProperties(obj) {
    let emptyKeys = [];
          for(let key in obj) {
          if(obj[key] === "") {
             emptyKeys.push(key + " is empty.\n");
    return emptyKeys.join('') + ' others keys are filled';

function isSorted (arr){
  return arr.every((a,b,c) => !b || c[b-1] <= a);

function shuffleArray (arr){
  let len = arr.length;
  while (len) {
    const i = Math.floor(Math.random() * len--);
    [arr[len], arr[i]] = [arr[i], arr[len]];
  return arr;

function generateRandomIntArr(len, upTo){
  return Array.from({ length: len }, () => Math.floor(Math.random() * upTo));

Also you can visit my github repo

thanks in advance


1 Answer 1


From a short review;

  • You may want to check out the lodash library, the implementation of isObject there is

    function isObject(value) {
      var type = typeof value;
      return value != null && (type == 'object' || type == 'function');
    • It does spell out completely value, which is better for readability
    • It does not repeat typeof value, but stores it in a temp value (would have gone for const here though)
    • It has one exit statement which seems cleaner
  • isDate returns true for 37, it feels wrong. I would try to parse numbers as well. Furthermore the functional name lies a bit, it does not check whether value is a date, but whether it can be converted to a date.

  • I prefer list more than arr, it reads better as a whole word

  • arr.every((a,b,c) -> those variable names are not good. every is not that common. I would if you insist on 1 letter variables go for v,i,l/a (value, index, list/array)

  • I would expect shuffleArray to create a new shuffled list, not to shuffle in place.

  • let emptyKeys could be const


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