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Javascript/ variable place/ what is wrong with the code

I want to write a Generator for Fibonacci numbers in Javascript;
0,1,1,2,5,7,12..... (to make the sequence you have to add the last two numbers)
But I have this problem when I assign the the output.length to a variable the code is not working, if I write it down straight instead of "newNumber" the code down is however working, but I don't understand what is wrong with the first one. Is it something wrong with the place of the variables?
function fibonacciGenerator(n) {
var output = [];
var lastNumber = output[output.length - 1];
var nPrev = output[output.length - 2];
var newNumber = lastNumber + nPrev;
if (n === 1) {
output = [0];
} else if (n === 2) {
output = [0, 1];
} else {
output = [0, 1];
for (var i = 2; i < n; i++) {
output.push(newNumber);
}
}
return output
}
console.log(fibonacciGenerator(5));

function fibonacciGen(n) {
const output = [0, 1];
// Return an empty array if n is less than 1
if (n < 1) {
return [];
}
// If n is 1 or 2, we can return the array now
if (n <2) {
return output;
}
// Loop through the remaining numbers in the sequence
for (let i = 2; i < n; i++) {
// Calculate the next number in the sequence
let lastNumber = output[output.length - 1];
let nPrev = output[output.length - 2];
let newNumber = lastNumber + nPrev;
// Add the new number to the output array
output.push(newNumber);
}
// Return the output array
return output;
}
console.log(fibonacciGen(5));

you have to declare your logic of next term in loop because first time length of output is zero
function fibonacciGenerator (n) {
var output =[];
if (n < 1) {
return [];
}
if (n===1){
output=[0];
}
else if (n===2){
output=[0,1];
}
else{
output=[0,1];
for( var i = 2; i < n; i++){
var lastNumber=output[output.length-1];
var nPrev=output[output.length-2];
var newNumber=lastNumber+nPrev;
output.push(newNumber);
}
}
return output
}

Fixing Fibonacci sequence script (javascript)

I am trying to write a script that will create numbers in Fibonacci order, I don't understand why this is not working.
var output = [];
var n = output.length;
var nextNum = output[n-1] + output[n-2];
function fibo (numQuantity) {
for (var i=1; i<numQuantity ; i++)
{
if (n>1){
output.push(nextNum);
console.log(output);
}
else if (n<2)
{output.push(1);
console.log(output);}
}
}

In your original code your n never changes as you only assigned it on start.
var output = [];
function fibo (numQuantity) {
for (var i=1; i<numQuantity ; i++)
{
var n = output.length;
var nextNum = output[n-1] + output[n-2];
if (n>1){
output.push(nextNum);
console.log(output);
}
else if (n<2)
{
output.push(1);
console.log(output);
}
}
}
fibo(10)
In Javascript numbers are passed by value not reference so they are not the same object in memory. So when the array length changes your n value stays at 0 because they are not the same object.

function fibo(numQuantity) {
let output = [0, 1];
if(numQuantity < 2) {
return output.slice(0, numQuantity);
}
for(let i = 2; i < numQuantity ; i++) {
const n = output.length
output.push(output[n - 1] + output[n - 2])
}
return output;
}
console.log(fibo(1))
console.log(fibo(2))
console.log(fibo(3))
console.log(fibo(4))

Check this fiddle: https://jsfiddle.net/37a4burz/
You need to add n++ to end of your code and change end condition.
Here is full code:
var output = [];
var n = output.length;
var nextNum = output[n-1] + output[n-2];
function fibo (numQuantity) {
for (var i=1; i<= numQuantity ; i++)
{
if (n==0) {
output.push(0);
console.log(output);
}
else if (n==1) {
output.push(1);
console.log(output);
}
else if (n>1) {
output.push(output[n-1] + output[n-2]);
console.log(output);
}
n++;
}
}
fibo(7);

How to get the product of numbers gotten from combinations of datasets

I have a combinatoric script that's working fine, actually got most of it from the IBM dev website. But I want to be able to not just show the possible combinations, but also extract the numbers on each combination and get the product of the entire numbers. The project am working on mixes numbers (quantity) with strings (codename). So after combining them, i extract the number from each string and get the product of all the numbers in each combination. As shown;
[A2,B4,C5] = 2*4*5 = 40
Here is my javascript code that gets the combination, not to worry, I ran it with a test array of numbers 1-6, without the characters as shown above.
var Util = function() {
};
Util.getCombinations = function(array, size, start, initialStuff, output) {
if (initialStuff.length >= size) {
output.push(initialStuff);
} else {
var i;
for (i = start; i < array.length; ++i) {
Util.getCombinations(array, size, i + 1, initialStuff.concat(array[i]), output);
}
}
}
Util.getAllPossibleCombinations = function(array, size, output) {
Util.getCombinations(array, size, 0, [], output);
}
// Create an array that holds numbers from 1 ... 6.
var array = [];
for (var i = 1; i <= 6; ++i) {
array[i - 1] = i;
}
var output = [];
var resultArray = [];
Util.getAllPossibleCombinations(array, 4, output);
for(var j=0; j<output.length; j++) {
resultArray += output[j] + "=" + "<br />";
}
document.getElementById("test").innerHTML = resultArray;
});
I tried running this code inside the last for loop to get my multiplication, but it's just not executing, i must be doing something wrong. Here is the code;
var inputval = output[j].replace(/[^,.0-9]/g, '');
inputval = inputval.slice(0, -1);
var hoArray = inputval.split(',');
var cunt= hoArray.length;
var ans=1;
for(var m=0; m<cunt; m++)
{
ans *= hoArray[m];
}
Thanks for your assistance in advance.

walk the array then walk the string, then cast and see if it is an integer then tally and sum the product.
let array = ['A20', 'B11', 'C5'];
function getProduct(ar) {
let product = 1;
for (let x of ar) {
let semiProduct = [];
for (let i of x) {
if (Number.isInteger(+i)) {
semiProduct.push(i);
}
}
product *= semiProduct.join('');
}
return product;
}
console.log(getProduct(array))
You could also use a regular expression.
let array = ['A20', 'B11', 'C5'];
function getProduct(ar) {
let product = 1;
for (let x of ar) {
product *= x.match(/\d+/)[0];
}
return product;
}
console.log(getProduct(array))
If you want a way to generate permutations, you can utilize a generator to make things more concise.
let array = ['A20', 'B11', 'C5'];
function* permu(arr, l = arr.length) {
if (l <= 0) yield arr.slice();
else
for (var i = 0; i < l; i++) {
yield* permu(arr, l - 1);
const j = l % 2 ? 0 : i;
[arr[l - 1], arr[j]] = [arr[j], arr[l - 1]];
}
}
console.log(
Array.from(permu(array))
);

When I run that code in the console it throws an error because output[j] is an array [1,2,3,4] and it looks like you're expecting it to be a string. Arrays do not have a replace method in JS.
You should run this:
var count= hoArray.length;
var ans=1;
for(var m=0; m<count; m++)
{
ans *= hoArray[m];
}
And put output[j] instead of hoArray. And don't do any of this:
var inputval = output[j].replace(/[^,.0-9]/g, '');
inputval = inputval.slice(0, -1);
var hoArray = inputval.split(',');

javascript array value is changing after it has been pushed

I am trying to debug the code below.
It is supposed to create a 2d-array, with all of the permutations of the input string.
It starts off great, and the initial string is pushed to the array, but after I run the reverse function in step 4, the value in strArr changes from having a length of 3 to a length of 2. basically like it is skipping the concat in the reverse function, but when I ran it in the debugger, z has a length of 3 after the concat, but then when the function returns it, the length becomes 2 again.
any help would be appreciated.
function permAlone(str) {
var perms = [];
var totalPerms = factorial(str.length);
var strCodes = converter(str);
var strArr = [];
strArr.push(strCodes);
// overall loop
for (var X = 0; X < totalPerms; X++) {
//step 1
var largestI = -1;
for (var i = 0; i < strCodes.length - 1; i++) {
if (strCodes[i] < strCodes[i + 1]) {
largestI = i;
}
}
//if none found break loop
if (largestI == -1) {
break;
}
//step 2
var largestJ = -1;
for (var j = 0; j < strCodes.length; j++) {
if (strCodes[largestI] < strCodes[j]) {
largestJ = j;
}
}
//step 3
swap(strCodes, largestI, largestJ);
//step 4
strCodes = reverse(strCodes, largestI);
//step 5 push to array
strArr.push(strCodes);
}
console.log(strArr);
return strArr;
}
function factorial(x) {
for (var i = x - 1; i > 0; i--) {
x *= i;
}
return x;
}
function converter(x) {
var temp = [];
for (var i = 0; i < x.length; i++) {
temp.push(x.charCodeAt(i));
}
return temp;
}
function swap(a, i, j) {
var temp = a[i];
a[i] = a[j];
a[j] = temp;
}
function reverse(z, a) {
var endArr = z.splice(a+1);
endArr.reverse();
z = z.concat(endArr);
return z;
}
debugger;
permAlone('abc');

The reverse function returns a new array and does not manipulate the existing. You need to change your code to the following:
endArr = endArr.reverse();

It looks like it was an issue with having a shallow copy of the array.
I added z = z.slice(); to the reverse function and it fixed the issue.

Array Processing logic correction

I have an array [1,2,4,5,1,7,8,9,2,3]
and i would like it to generate all subset which sum of values are less than 10
current result [[1,2,4],[5,1],[7],[8],[9],[2,3]]
expected result [[4,5,1],[9,1],[8,2],[3,7],[1,2]]
that is what i did
var a = [1,2,4,5,1,7,8,9,2,3], tempArr = []; tempSum = 0, result = [];
for (var i = 0;i< a.length; i += 1 ) {
tempSum+=a[i];
tempArr.push(a[i]);
if((tempSum+a[i+1])>10) {
result.push(tempArr);
tempSum = 0;
tempArr = [];
} else if (i == a.length-1 && tempArr.length > 0) { // if array is [1,2,3]
result.push(tempArr);
}
}
but it gives me [[1,2,4],[5,1],[7],[8],[9],[2,3]] and it has 6 subset, but i expect to get [[4,5,1],[9,1],[8,2],[3,7],[1,2]] which has 5 subset.

Below logic is in JavaScript :-
var limit = 10;
var arr = [1,2,4,5,1,7,8,9,2,3];
arr.sort();
var ans = new Array ( );
while(arr.length >0){
var ts = arr[arr.length-1];
arr.splice(arr.length-1 , 1);
var ta= new Array ( );
ta.push(ts);
var x = arr.length-1;
while(x>=0){
if(ts + arr[x] <= limit){
ts = ts + arr[x];
ta.push(arr[x]);
arr.splice(x , 1);
}
x= x-1;
}
ans.push(JSON.stringify(ta));
}
alert(ans);
It is Giving Output as required .
[9,1],[8,2],[7,3],[5,4,1],[2]

I have removed duplicates then added maxSum parameter to combine function to generate all subset which have those conditions and then sorted subsets by sum of the values and sliced them.
You could change parameters to fit it for your problem.
var arr = [1,2,4,5,1,7,8,9,2,3]
MAX_SUM = 10,
MIN_SUBSET_LEN = 2,
RESULT_LEN = 5;
//remove duplicates
var uniqeSet = arr.filter(function(value, index){
return this.indexOf(value) == index
},arr);
// a function to get all subset which
// their length are greater than minLength and
// sum of values are little than maxSum
var combine = function(sourceArr, minLength, maxSum) {
var fn = function(n, src, got, all, sum) {
if(sum <= maxSum){
if (n == 0) {
if (got.length > 0) {
all.push({arr:got,sum:sum});
}
return;
}
for (var j = 0; j < src.length; j++) {
var tempSum = sum
fn(n - 1, src.slice(j + 1), got.concat([src[j]]), all, sum + src[j]);
}
}
return;
}
var all = [];
for (var i = minLength; i < sourceArr.length; i++) {
fn(i, sourceArr, [], all, 0);
}
return all;
}
var result = combine(uniqeSet, MIN_SUBSET_LEN, MAX_SUM);
var sortedSliced = result.sort(function(a1, a2){
return a2.sum - a1.sum;
}).slice(0, RESULT_LEN).map(function(m){return m.arr;});
console.log(JSON.stringify(sortedSliced));