@Abulkhair1995
love you nader you deserve the best
@thandomncube3480
I was able to smash to warm-up actually and flatten the array. Still need more practice for myself I must say.
@mdd972
Thank you Nader for the amazing content! I've been following the entire javascript series and this lesson is the hardest so far, I feel like I understand "recursion' but when it comes to the exercices I really struggled
@tomboolery
I'm not even gonna lie these exercises hurt. I thought I had a good enough grasp on the topic just off of the lecture but it's clear this is just going to be something I need to practice more.
I was only able to solve two of these exercises, with one being the warmup and the other being exercise 2. The thing is I solved exercise 2 in an entirely differently way and kind of feel like I cheated (?) after seeing your solution:
// GOAL: Create a function that takes an array as its argument. The function must return a flattened version of the array no matter how NESTED it is.
const flatten = (arr) => {
// Array.isArray() evaluates whatever value is passed into it and determines whether or not it is an array!
if (Array.isArray(arr) === true) {
return console.log(`${arr}`);
}
if (Array.isArray(arr) === false) {
return console.log(`${arr}, is not an array`);
}
// .flat() is an ARRAY METHOD that flattens all nested arrays. It creates a new, flattened array =)
return flatten(arr.flat(arr));
};
console.log(flatten([1, 2, 3]));
console.log(flatten([1, 2, 3, [1, 2, 3]]));
console.log(flatten([1, [4, 5, 6, [7, 8, 9]], 2, 3]));
console.log(flatten("ayo"));
I'm hoping to move onto react and the DOM series soon but I really want to ensure my JS is as sharp as it can be. Feeling humbled. Tough stuff. Thanks as always Nader.
@frq9293
Took me ages but this was my solution for flatten... I was trying to not use loops at all for some reason
function flatten(arr, i=0){
if(i===arr.length-1) return arr
if(!Array.isArray(arr[i])) return flatten(arr, i+1)
const sub = arr[i];
arr.splice(i, 1)
arr.splice(i, 0, ...sub)
return flatten(arr, i)
}
@erahia8702
just wanted to say your videos are really helpful, thanks!
@Gerrrawwrr
Hi Nader! I used a ready function for exercise #2. Well i used the "Array.flat()". And here it is my code :
const flatten = (arr) => {
array_flatened = arr.flat();
for (element of array_flatened) {
if (typeof element === "object") {
flatten(array_flatened);
}
}
return array_flatened;
};
@timothyrees6318
Great video as always! But very difficult topic. Took me many hours. This is my solution to exercise 2:
let flat = [];
const flatten = (arr)=>{
for(let i = 0; i<arr.length;i++){
if(!Array.isArray(arr[i])){
flat.push(arr[i])
}
else flatten(arr[i])
}
return flat;
}
@Kerwell
i think the hardest thing about recursion is the mentality you have to adopt. Took me 2 days and fully gave up on bonus exercise. It makes sense in retrospect, but it takes me a really long time to think in recursion.
ex1.
const palindrome = (string) => {
if (string.length === 0) return false;
if (string.length === 1) return true;
if (string[0] === string[1]) return true;
if (string[0] !== string[string.length - 1]) return false;
if (string[0] === string[string.length - 1]) {
let arr = string.split(""); // convert string to array
arr.pop();
arr.shift();
string = arr.join("");
return palindrome(string);
}
};
ex2. this one was no joke, i just assume we couldn't use any loops until I saw how you solved it lol...
const flatten = (array) => {
if (array.length === 0) {
return array;
}
if (Array.isArray(array[0])) {
array.splice(0, 1, ...array[0]);
return flatten(array);
}
return [array[0], ...flatten(array.slice(1))];
};
ex3.
const flatten = (object) => {
let flattened = {};
for (const [key, value] of Object.entries(object)) {
if (typeof value === "object") {
flattened = { ...object[key] };
delete object[key];
return flatten((flattened = { ...object, ...flattened }));
}
}
return object;
};
I fully gave up on bonus exercise. It was easy in retrospect, but it's really hard for me to adopt the thought process.
@kamilzmuda694
Great channel and videos! π
It's a real pleasure to learn following your tutorials.
I would like to get some feedback about my solution for exercise 2 - flatten the array. Let me know what you guys think! π
CODE:
const flatten = (arr) => {
if (!arr.some(element => Array.isArray(element))) { // base case - check if at least 1 element of passed array is an array, if not return we arr
return arr;
} else {
arr = arr.flat() // if any of the elements is an array we assign arr.flat( ) to arr and make a recursive call by passing arr flattened by 1 level
return flatten(arr)
}
}
@aissanadjemeddine1330
Thanks for this amazing video , very helpful
@jjjj5452
this one kicked my butt
@644sixfortyfour4
With these advanced topics, I'm starting to really appreciate your long videos Nader, especially the exercises, so thank you for putting so much into these videos. π I did take my time to solve the exercises myself first, and went through your solutions after, but I will need more time to master it though.
@ShivamSharma-dq4pu
function flatten(array) {
let result = [];
for (const item of array) {
if (Array.isArray(item)) {
result = [...result, ...flatten(item)];
} else {
result.push(item);
}
}
return result;
}
console.log(flatten([1, 2, 3]));
console.log(flatten([1, 2, 3, [1, 2, 3]]));
console.log(flatten([1, [4, 5, 6, [7, 8, 9]], 2, 3]));
@dimadeloseros1
Dude keep it up. Your videos are extremely helpful to me. I love your way of teaching / followed by a video of exercises. I'm sure that you will get lots of subs in no time.
@kodyn384
Here's my solution to Exercise 2:
function flatten(arr) {
const nextNestedArray = arr.find(el => Array.isArray(el));
const indexOfNextNestedArray = arr.indexOf(nextNestedArray);
// Base cases:
if(arr.length === 0 || !nextNestedArray) return arr;
// Recursive case:
let newArr = arr.toSpliced(indexOfNextNestedArray, 1, ...nextNestedArray);
return flatten(newArr);
}
@ThanhTran-vn8tp
Here is my version of the bonus exercise:
const constructDOM = (object) => {
let result = "";
for (const [key, value] of Object.entries(object)) {
if (key === "nodeName") {
result += `<${value}>`;
}
if (key === "childNodes") {
for (const obj of value) {
result += constructDOM(obj);
}
if (Object.hasOwn(object, 'nodeName')) {
result += `</${object.nodeName}>`;
}
}
if (key === "innerText") {
result += `${value}</${object.nodeName}>`;
}
}
return result;
}
@EliHacΔ±yev-p7v
Thanks π
@akashrattan2975
Love the video, in-depth exercises, and everything on the video π― overall!!!!! Thanks for the constant uploads π
@thandomncube3480