As in, https://github.com/bcherny/frontend-interview-questions/blob/master/coding-intermediate/assignDeep.js

if you try to call it with let s = assignDeep({a:1}, {b: new Date()}), you get an object: {a:1, b: {}}, rather than {a:1, b: date object}.

The reason lies in:

function isObject(a) { return typeof a === 'object' && a !== null}

if you try to call it as: isObject(new Date()), it returns true, therefore it going to be treated the date as an iterable object, I mean, it recursively call the assignDeep method on the date object.

however, during my tests, function isObject(a) { return typeof a === 'object' && a !== null&& Object.keys(a).length>0 , can be a good solution to check if this source[key] is an interable object.

Current implementation

function reverse(string) {
  let index = string.length - 1
  let result = ''
  while (index > -1) {
    result += string[index]
    index--
  }
  return result
}

same as this one (short and popular one)

function reverse(string) {
    return string.split('').reverse().join('');
}

Both wont work with with Unicode chars which length is more than 16 bit (surrogate pairs).
Because both split('') and string[i] will address characters by 16 bit blocks, and so destroy Unicode pairs.

Ex.:

reverse('abc 🚀') // Error: expected '�� cba' to equal '🚀 cba'

Solution is es6 string[Symbol.iterator] via destructuring, which takes Unicode chars into account (proof):

function reverse(str) {
  return [...str].reverse().join('');
}

Probably you want to keep answers as transparent as possible and split().reverse().join() is too hack-ish for educational purposes. But maybe you can mention Unicode issue in the comment above the solution for people to know. Cheers.

URL links to the question doesn't load.

Since we want to try to solve the questions before reading the solution, could you please try to solve this issue?

Source test on github is ok, but blog post has issue:

isBalanced('{}{}')                    // false

Should be true.

isBalanced('}{'); // true

I guess it depends on what you call balanced 😛

Could test that count >= 0 before count--, return false if not.

Original question

let tree = new BinarySearchTree
tree.add(1, 2, 3, 4)
tree.add(5)
tree.has(2)                           // true
tree.has(5)                           // true
tree.remove(3)                        // undefined
tree.size()                           // 3

Should be tree.size() // 4 (total number of nodes)

Or maybe tree.depth() // 3 (highest distance from root, in case it is not self-balancing BST)

Hello,
Thanks for putting this together, I was just browsing and noticed a bug in implementation of isPrime. It returns wrong results.

Try:

isPrime(9); // -> true
isPrime(21); // -> true
isPrime(25); // -> true

And none of these is prime. It will return true for any odd number, as you are skipping all of the odd number dividers (counter has a value of 2 + (n * 2)) on the line #17

  for (let i = 2; i < Math.ceil(Math.sqrt(n)); i += 2) {
    if (n % i === 0) {
      return false
    }
  }

You just need to increment by 1 not by 2.

Cheers!