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Shuffle nested arrays in Javascript

I'm trying to sort multiple arrays within an array (which also has to be shuffled). A simplified example is:
let toShuffle = [
[1, 2, 3, 4, 5],
[9, 8, 7, 6, 5],
[10, 67, 19 ,27]
...
];
const shuffled = shuffle(toShuffle);
// outout would look something like:
// [
// [8, 6, 5, 7, 9],
// [4, 3, 1, 5, 2],
// [19, 26, 10, 67],
// ...
// ]
This needs to be flexible, so any number of arrays with any amount of values should be valid.
Here is what I've tried:
function shuffle(a) {
for (let e in a) {
if (Array.isArray(a[e])) {
a[e] = shuffle(a[e]);
} else {
a.splice(e, 1);
a.splice(Math.floor(Math.random() * a.length), 0, a[e]);
}
}
return a;
}
console.log("Shuffled: " + shuffle([
[1, 2, 3, 4, 5],
[5, 4, 3, 2, 1]
]))
But it's not working as intended. Is their an easier way to do this? Or is my code correct and just buggy.

You can use Array.from() to create a new shallow-copied array and then to shuffle Array.prototype.sort() combined with Math.random()
Code:
const toShuffle = [
[1, 2, 3, 4, 5],
[9, 8, 7, 6, 5],
[10, 67, 19 ,27]
]
const shuffle = a => Array.from(a).sort(() => .5 - Math.random())
const result = toShuffle.map(shuffle)
console.log('Shuffled:', JSON.stringify(result))
console.log('To shuffle:', JSON.stringify(toShuffle))

You almost got it. The problem is that you are removing one item from an array, instead of capturing the removed item and them placing in a random position:
let toShuffle = [
[1, 2, 3, 4, 5],
[9, 8, 7, 6, 5],
[10, 67, 19 ,27]
];
function shuffle(a) {
a = [...a]; //clone array
for (let e in a) {
if (Array.isArray(a[e])) {
a[e] = shuffle(a[e]);
} else {
a.splice(~~(Math.random() * a.length), 0, a.splice(e, 1)[0]);
}
}
return a;
}
console.log(JSON.stringify(shuffle(toShuffle)))
console.log(JSON.stringify(toShuffle))
[EDIT]
The original code did not shuffle the parent array, if you need shuffle everything recursively, you can use this:
let toShuffle = [
[1, 2, 3, 4, 5],
[9, 8, 7, 6, 5],
[10, 67, 19 ,27]
];
function shuffle(a) {
a = a.map(i => Array.isArray(i) ? shuffle(i) : i); //clone array
a.sort(i => ~~(Math.random() * 2) - 1); //shuffle
return a;
}
console.log("shuffled", JSON.stringify(shuffle(toShuffle)))
console.log("original", JSON.stringify(toShuffle))

How to map an array of arrays and just return it

I have an array of arrays, and I want to map over it and just return the values of arrays, but when I map over it and log the result, it's just an array and I don't know how to map over my array and use it in other places.
const arr = [
[1, 2, 3],
[4, 5, 6],
[7, 8, 9],
];
const arrMap = arr.map((it) => it.map((itm) => itm));
console.log(arrMap);
//what I expected 1,2,3,4,5,6 , ...
//what I got [Array(3), Array(3), Array(3)]
Actually, I need the values for using them in somewhere else, but I don't know what to do.
I also used function for this but when I return the values and log them It's undefined:
const arr = [
[1, 2, 3],
[4, 5, 6],
[7, 8, 9],
];
const arrMap = (arr) => {
arr.forEach((element) => {
console.log(element);
//In here, everything works fine
return element;
});
};
console.log(arrMap);
//what I got undefined

Use flatMap -
const arr = [
[1, 2, 3],
[4, 5, 6],
[7, 8, 9],
];
const arrMap = arr.flatMap(m => m);
console.log(arrMap);

Why it won't work : map() is supposed to run on each element of an array and return a transformed array of the same length. You have three elements in your input array and will always get three elements in your mapped array.
Your expectations can be met by tweaking your code with forEach() if you want. With forEach() there is nothing returned and you will have to start with a separate array variable. Below code uses ...
const arr = [
[1, 2, 3],
[4, 5, 6],
[7, 8, 9],
];
let arrMap = [];
arr.forEach((it) => arrMap.push(...it));
console.log(arrMap);
But flatMap() is already there:
const arr = [
[1, 2, 3],
[4, 5, 6],
[7, 8, 9],
];
let ans = arr.flatMap(x => x);
console.log(ans);

Use flat if you just want to flatten the array:
const arr = [
[1, 2, 3],
[4, 5, 6],
[7, 8, 9],
];
console.log(arr.flat());
Use flatMap if you want to do something with each element before the array gets flattened.
const arr = [
[1, 2, 3],
[4, 5, 6],
[7, 8, 9],
];
const arrMap = arr.flatMap((el) => {
el.forEach((n) => console.log(n));
return el;
});
console.log(arrMap);

forEach doesn't return anything it's like a for loop but for array only.
Since you have double array you should flat it by using flatMap
const arr = [
[1, 2, 3],
[4, 5, 6],
[7, 8, 9],
];
const arrMap = arr.flatMap((it) => it);
console.log(arrMap);

how to form array of arrays from object array in java script

Am trying form data from object array to array of arrays in JavaScript but am unable to get the result
Input Data { "sept" : [1,2,3], "oct" : [5,6,7] "Nov" : [7,8,9]}
Expected Output [["sept",1,2,3],["oct",5,6,7],["Nov",7,8,9]]
I have tried a lot I can able to get the keys by Object.Key() but can able to form the data with the value as expected output above, please help me to resolve this Thanks in advance

You could get the entries and map key and values in an array.
const
data = { sept: [1, 2, 3], oct: [5, 6, 7], Nov: [7, 8, 9] },
result = Object.entries(data).map(([k, v]) => [k, ...v]);
console.log(result);

Just iterate over properties using for .. in loop, you will get the result.
const obj = {
"sept": [1, 2, 3],
"oct": [5, 6, 7],
"Nov": [7, 8, 9],
}
const result = [];
for (const prop in obj) {
result.push([prop, ...obj[prop]]);
}
console.log(result)

Use Object.entries() and then .map() with ... - rest/spread operator
const object = {
september: [1, 2, 3],
october: [5, 6, 7],
november: [7, 8, 9],
}
const result = Object.entries(object).map(([key, value])=>[key, ...value])

You could use Object.entries then spread the values along with the key
const data = { sept: [1, 2, 3], oct: [5, 6, 7], Nov: [7, 8, 9] }
const res = Object.entries(data).map(([key, value]) => [key, ...value])
console.log(res)

The Ramda.js library has a function that does exactly this called toPairs()
https://ramdajs.com/docs/#toPairs

find the smallest number in a array of an array

i'm trying to write a function to find the smallest number on an array of an array.
already tryed this, but i don't really know how to do when there is arrays on an array.
const arr = [4, 8, 2, 7, 6, 42, 41, 77, 32, 9]
const min = Math.min(arr)
console.log(min)

By taking ES6, you could use the spread syntax ..., which takes an array as arguments.
const arr = [4, 8, 2, 7, 6, 42, 41, 77, 32, 9];
const min = Math.min(...arr);
console.log(min);
With ES5, you could take Function#apply, which take this and the parameters as array.
const arr = [4, 8, 2, 7, 6, 42, 41, 77, 32, 9];
const min = Math.min.apply(null, arr);
console.log(min);
For unflat arrays, take a flatten function, like
const
flat = array => array.reduce((r, a) => r.concat(Array.isArray(a) ? flat(a) : a), []),
array = [[1, 2], [3, 4]],
min = Math.min(...flat(array));
console.log(min);

You can use map to iterate over the nested arrays and then use Math.min(...array) on each to get the minimum. The output from map is an array of minimum values.
const arr = [[4, 8, 2], [7, 6, 42], [41, 77, 32, 9]];
const out = arr.map(a => Math.min(...a));
console.log(out);

Use spread ... and flat:
const a = [[0, 45, 2], [3, 6, 2], [1, 5, 9]];
console.log(Math.min(...a.flat()));
Or you might use reduce:
const arr = [[7, 45, 2], [3, 6, 2], [1, 5, 9]];
let r = arr.reduce((a, e) => Math.min(a, ...e), Infinity)
console.log(r);

JavaScript. How to Compare Input Arrays

I'm stuck with this problem for 3 days now... Someone please help me.
Challenge 5
Construct a function intersection that compares input arrays and returns a new array with elements found in all of the inputs.
function intersection(arrayOfArrays) {
}
console.log(intersection([[5, 10, 15, 20], [15, 88, 1, 5, 7], [1, 10, 15, 5, 20]]));
// should log: [5, 15]

Reduce the arrays to a Map of counts, with the value as key. Spread the Map to entries. Use Array.filter() on the Map's entries to remove all entries, which value is not equal to the arrayOfArrays lenth. Extract the original number from the entries using Array.map():
function intersection(arrayOfArrays) {
return [...arrayOfArrays.reduce((r, s) => {
s.forEach((n) => r.set(n, (r.get(n) || 0) + 1));
return r;
}, new Map())]
.filter(([k, v]) => v === arrayOfArrays.length)
.map(([k]) => k);
}
console.log(intersection([[5, 10, 15, 20], [15, 88, 1, 5, 7], [1, 10, 15, 5, 20]]));

You could reduce the array by filtering with just checking if the other array contains the value.
This works for arrays with unique values.
Array#reduce:
If no initialValue is provided, then accumulator will be equal to the first value in the array, and currentValue will be equal to the second.
The callback
a.filter(v => b.includes(v))
filters array a. If the array b includes the value of a, then this value v is included in the accumulator for the next iteration or as final result.
accumulator currentValue new accumulator
a b result
-------------------- -------------------- --------------------
[ 5, 10, 15, 20] [15, 88, 1, 5, 7] [ 5, 15]
[ 5, 15] [ 1, 10, 15, 5, 20] [ 5, 15]
function intersection(arrayOfArrays) {
return arrayOfArrays.reduce((a, b) => a.filter(v => b.includes(v)));
}
console.log(intersection([[5, 10, 15, 20], [15, 88, 1, 5, 7], [1, 10, 15, 5, 20]]));

First try to find out the intersection of two arrays which is the base problem. Then try to build up for variable number of arrays passed as arguments for intersection. You can use reduce() for doing that.
function intersectionOfTwoArrays(arr1, arr2)
{
return arr1.filter(x => arr2.some(y => y === x));
}
function intersection(...arrayOfArrays)
{
return arrayOfArrays
.reduce((a, b) => intersectionOfTwoArrays(a, b));
}
intersection(
[5, 10, 15, 20],
[15, 88, 1, 5, 7],
[1, 10, 15, 5, 20]
);

You can go through the first array in the array of arrays and check which of its value is present in all the other arrays.
Here is an example:
function intersection(input) {
let firstArray = input[0];
let restOfArrays = input.splice(1);
return firstArray.filter(v => restOfArrays.every(arr => arr.includes(v)));
}
const input = [[5, 10, 15, 20], [15, 88, 1, 5, 7], [1, 10, 15, 5, 20]];
const result = intersection(input);
console.log(result);

Works with even if there is duplicate in same array.. like in my example added 5 twice in arrayEle[1];
var arrayEle = [[5, 10, 15, 20], [15, 88, 1, 5, 5], [1, 10, 15, 5, 20]]
var startIndex = 1;
var newArray = [];
for (var x = 0; x < arrayEle[0].length; x++) {
var temVal = 1;
var value;
for (var y = 1; y < arrayEle.length; y++) {
for (var z = 0; z < arrayEle[y].length; z++) {
if (arrayEle[y][z] == arrayEle[0][x]) {
temVal++;
value = arrayEle[y][z];
break;
}
}
}
if (temVal == arrayEle.length) {
newArray.push(value);
console.log(value);
}
}
console.log(newArray);
//log: [5, 15]

I think you want the common elements. Let me show you how:
var Array1 = [5, 10, 15, 20]
var Array2 = [15, 88, 1, 5, 7]
var Array3 = [1, 10, 15, 5, 20]
var found = []
var Final = []
var c = 1;e = 1;
for (i = 1;i<=Array1.length;i++){
for (k = 1;k<=Array2.length;i++){
if (Array1[i] == Array2[k]){
Found[c] = Array[i];
c++;
}
}
}
for (n = 1;n <= Found.length ; n++){
for (m = 1;m <= Array3.length ; n++){
if (Found[n] == Array3[m]){
Final[e] = Found[n]
e++;
}
}
}
//the Array Final Contains 5 , 15