Develop Reference

How do I add the number to the variable in Javascript?

I need to guess the 4-digit code by this program, but I have no idea why it doesn't work.
I tried to use two for loops to guess all of the numbers from 0 to 9 for 4 digits.
However, the program doesn't print anything.
I wonder how can I add the current value x to the variable result.
function start() {
var secretPasscode = generateRandomPasscode();
// Write your code here
var result = "";
//Loop through for the secretPasscode's length
for(var i = 0; i < secretPasscode.length; i++){
//Put numbers from 0 to 9
for(var x = 0; x < 10; x++){
result = "";
var currNum = x;
//If the current number is right, store it to the result
if(currNum == secretPasscode.charAt(i)){
result += x;
}else{
result = result;
}
}
}
return result;
println(result);
}
function isCorrect(guessCode, correctCode) {
return guessCode == correctCode;
}
// Generates a random 4 digit passcode and returns it as a String
function generateRandomPasscode() {
var randomPasscode = "";
for(var i = 0; i < 4; i++) {
var randomDigit = Randomizer.nextInt(0, 9);
randomPasscode += randomDigit;
}
return randomPasscode;
}

How do you iterate over an array every x spots and replace with letter?

/Write a function called weave that accepts an input string and number. The function should return the string with every xth character replaced with an 'x'./
function weave(word,numSkip) {
let myString = word.split("");
numSkip -= 1;
for(let i = 0; i < myString.length; i++)
{
numSkip += numSkip;
myString[numSkip] = "x";
}
let newString = myString.join();
console.log(newString);
}
weave("weave",2);
I keep getting an infinite loop. I believe the answer I am looking for is "wxaxe".

Here's another solution, incrementing the for loop by the numToSkip parameter.
function weave(word, numToSkip) {
let letters = word.split("");
for (let i=numToSkip - 1; i < letters.length; i = i + numToSkip) {
letters[i] = "x"
}
return letters.join("");
}

Well you need to test each loop to check if it's a skip or not. Something as simple as the following will do:
function weave(word,numSkip) {
var arr = word.split("");
for(var i = 0; i < arr.length; i++)
{
if((i+1) % numSkip == 0) {
arr[i] = "x";
}
}
return arr.join("");
}
Here is a working example
Alternatively, you could use the map function:
function weave(word, numSkip) {
var arr = word.split("");
arr = arr.map(function(letter, index) {
return (index + 1) % numSkip ? letter : 'x';
});
return arr.join("");
}
Here is a working example
Here is a more re-usable function that allows specifying the character used for substitution:
function weave(input, skip, substitute) {
return input.split("").map(function(letter, index) {
return (index + 1) % skip ? letter : substitute;
}).join("");
}
Called like:
var result = weave('weave', 2, 'x');
Here is a working example

You dont need an array, string concatenation will do it, as well as the modulo operator:
function weave(str,x){
var result = "";
for(var i = 0; i < str.length; i++){
result += (i && (i+1)%x === 0)?"x":str[i];
}
return result;
}
With arrays:
const weave = (str,x) => str.split("").map((c,i)=>(i&&!((i+1)%x))?"x":c).join("");

You're getting your word greater in your loop every time, so your loop is infinite.
Try something like this :
for(let k = 1; k <= myString.length; k++)
{
if(k % numSkip == 0){
myString[k-1]='x';
}
}

Looking at what you have, I believe the reason you are getting an error is because the way you update numSkip, it eventually becomes larger than
myString.length. In my code snippet, I make i increment by numSkip which prevents the loop from ever executing when i is greater than myString.length. Please feel free to ask questions, and I will do my best to clarify!
JSFiddle of my solution (view the developer console to see the output.
function weave(word,numSkip) {
let myString = word.split("");
for(let i = numSkip - 1; i < myString.length; i += numSkip)
{
myString[i] = "x";
}
let newString = myString.join();
console.log(newString);
}
weave("weave",2);

Strings are immutable, you need a new string for the result and concat the actual character or the replacement.
function weave(word, numSkip) {
var i, result = '';
for (i = 0; i < word.length; i++) {
result += (i + 1) % numSkip ? word[i] : 'x';
}
return result;
}
console.log(weave("weave", 2));
console.log(weave("abcd efgh ijkl m", 5));

You can do this with fewer lines of code:
function weave(word, numSkip) {
word = word.split("");
for (i = 0; i < word.length; i++) {
word[i] = ((i + 1) % numSkip == 0) ? "x" : word[i];
}
return word.join("");
}
var result = weave("weave", 2);
console.log(result);

Palindrome function returns true when word isn't a palindrome

Could someone be kind enough to tell me why "almostomla" returns true in my code.
I have searched and have seen there are simpler versions but im so deep into this code now i need to make it work if at all possible.
Please excuse the terrible variable names, i was frustrated.
function palindrome(str) {
str = str.toLowerCase();
str = str.replace(/ /g, '').replace(/\./g, '').replace(/,/g, '');
for (var i = 0; i < str.length / 2; i++) {
for (var j = str.length - 1; j > str.length / 2 - 1; j--) {
var iDntKnow = str.charAt(i);
var iDntKnowEither = str.charAt(j);
if (iDntKnow === iDntKnowEither) {
return true;
} else {
return false;
}
}
}
}
Appreciate all answers.

While I can understand the frustration of wanting to make something work if you have put time into it, there is also something to be said for starting from the drawing board and not driving yourself crazy. The main problem I see with your code is that you have two loops when you only need one. The second loop is actually sabotaging you. I would suggest running a debugger (type "debugger" into your code and run) to see why.
I believe this is what you are trying to accomplish:
var palindrome = function(str) {
// Put any additional string preprocessing here.
for(var i = 0; i < str.length/2; i++) {
var j = str.length-i-1;
if (str[i] != str[j]) {
return false;
}
}
return true;
}
In this way you are comparing each mirrored element in the string to confirm if the string is a palindrome.

Your question seems to be answered by now.
If performance isn't an issue, why not just use this?
function palindrome(str) {
str = str.toLowerCase();
return (str.split().reverse().join() === str)
}
It splits the string into an array, reverses that and joins it back together. The result is compared to the original string.

You can only know if it's NOT a palindrome in each iteration.
Also, why using nested loops?
function palindrome(str) {
str = str.toLowerCase();
str = str.replace(/ /g, '').replace(/\./g, '').replace(/,/g, '');
for (var i = 0; i < str.length / 2; i++) {
if (str.charAt(i) !== str.charAt(str.length - i - 1)) {
return false;
}
}
return true;
}

This works:
function palindrome(string) {
string = string.toLowerCase();
for (var i = 0; i < Math.ceil(str.length/2); i++) {
var character1 = string.charAt(i);
var character2 = string.charAt(string.length-1-i);
if (character1 !== character2) {
return false;
}
}
return true;
}

Here is a version that omits spaces and commas:
var removeLetterFromString = function(string,letterPos){
var returnString = "";
for(var i = 0; i < string.length; i++){
if(i!==letterPos){
returnString=returnString+string.charAt(i);
}
}
return returnString;
};
var palindrome = function(string) {
string = string.toLowerCase();
var stringCheck="";
var recheck = true;
while(recheck){
recheck=false;
for(var i = 0; i < string.length; i ++){
if(string.charAt(i)===" "||string.charAt(i)===","){
string=removeLetterFromString(string,i);
}
}
for(var i = 0; i < string.length; i ++){
if(string.charAt(i)===" "||string.charAt(i)===","){
recheck=true;
}
}
}
if(string.length===0){
return false;
}
for (var i = 0; i < Math.ceil(string.length/2); i++) {
var j = string.length-1-i;
var character1 = string.charAt(i);
var character2 = string.charAt(j);
if (character1 !== character2) {
return false;
}
}
return true;
};

formatMoney function in Javascript doesn't work

I need a function which can transform the number 10000 to this number: 10.000.
So I tried the following:
function formatMoney(money){
var value = money.toString();
var l = value.length;
var new_value = 0;
new_value = new_value.toString();
if(l > 3){
var moneyarray = value.split('');
var u = 0;
for(i = l;i >= 0;i--){
if(u > 3){
u = 0;
new_value = "."+new_value;
}
new_value = moneyarray[i]+new_value;
u++;
}
}
return new_value;
}
And then call this:
formatMoney("10000");
But the result is
10.000undefined0"
What did I do wrong?

You're assigning the index counter to the length of the string;
var l = value.length;
...
for(i = l;i >= 0;i--){
And the down count starts with the length-index, which isn't present since arrays are zero-based. Subtract beforehand instead;
for(i = l;i >= 0;--i){

EDIT: Disregard this, I wasn't paying enough attention to the question.
If all you're looking to do is take numbers that are 4 digits or greater and put a dot in three digits from the right, you could give this a shot:
function formatMoney(money) {
var moneyString = money.toString();
var moneyLength = moneyString.length;
if(moneyLength < 4) {
return 0;
}
var dotIndex = moneyLength - 3;
return moneyString.substr(0, dotIndex) + "." + moneyString.substr(dotIndex);
}
Also, formatting your code in the post is good stuff. Indent it all by four spaces.

function formatMoney(money){
var value = money.toString();
var l = value.length;
var new_value = 0;
new_value = new_value.toString();
if(l > 3){
var moneyarray = value.split('');
for(var i = l-1;i >= 0;i--){
if((l-i)%3 === 0){
new_value = "."+new_value;
}
new_value = moneyarray[i]+new_value;
}
} else {
new_value = value;
}
return new_value;
}
A couple of things:
You were counting down with the wrong index (you were starting at l, instead of l-1)
You were not handling any value less than 1000
You don't need to use a counter variable u, you can just use modulo math to keep track of threes.

I cut off some parts:
function formatMoney(money) {
var value = money.toString();
var l = value.length;
var new_value = "";
if (l > 3) {
var u = 0;
for (i = l-1;i >= 0;i--) {
if (u == 3) {
u = 0;
new_value = "." + new_value;
}
new_value = value[i]+new_value;
u++;
}
}
return new_value;
}

You could do it like this:
function money(m) {
m = m.toString().split('');
for (var i = m.length - 3; i > 0; i -= 3)
m.splice(i,0,".");
return m.join('');
}
console.log(money(1000000)); // "1.000.000
See this JsBin

How to modify this function to return string instead of int

please take a quick look at this function that I have found on the web.
function longestCommonSubstring(string1, string2){
// init max value
var longestCommonSubstring = 0;
// init 2D array with 0
var table = Array(string1.length);
for(a = 0; a <= string1.length; a++){
table[a] = Array(string2.length);
for(b = 0; b <= string2.length; b++){
table[a][b] = 0;
}
}
// fill table
for(var i = 0; i < string1.length; i++){
for(var j = 0; j < string2.length; j++){
if(string1[i]==string2[j]){
if(table[i][j] == 0){
table[i+1][j+1] = 1;
} else {
table[i+1][j+1] = table[i][j] + 1;
}
if(table[i+1][j+1] > longestCommonSubstring){
longestCommonSubstring = table[i+1][j+1];
}
} else {
table[i+1][j+1] = 0;
}
}
}
return longestCommonSubstring;
}
It returns the length of the longest common substring as an int. Now to my question, is it possible to modify this function, so that it returns the actual string instead of just returning the length of the substring, I'm quite new at programming and thought that just modifying this secetion would help if(string1[i]==string2[j]){ push(string1[i]}, but it isn't that easy, because I don't want every single character that is the same in those 2 strings to be added in that array, only those that are exactly the same.
Thanks in advance =)

Well for minimal changes to the existing function you could declare a new variable:
var theCommonString = '';
Then in the middle of the function add a line after this existing one:
longestCommonSubstring = table[i+1][j+1];
that says something like:
theCommonString = string1.substr(i + 1 - longestCommonSubstring,
longestCommonSubstring);
(That i + 1 index may be a little off, I haven't bothered working it out carefully.)
Then at the end just return your new variable instead of the existing one.
Note that if there is more than one common sub string of the same length this will return the last one.

You can just store the whole common substring in the table instead of its length:
function longestCommonSubstring(string1, string2){
// init max value
var longestCommonSubstring = "";
// init 2D array with 0
var table = Array(string1.length);
for(a = 0; a <= string1.length; a++){
table[a] = Array(string2.length);
for(b = 0; b <= string2.length; b++){
table[a][b] = 0;
}
}
// fill table
for(var i = 0; i < string1.length; i++){
for(var j = 0; j < string2.length; j++){
if(string1[i]==string2[j]){
if(table[i][j] == 0){
table[i+1][j+1] = string1[i];
} else {
table[i+1][j+1] = table[i][j] + string1[i];
}
if(table[i+1][j+1].length > longestCommonSubstring.length){
longestCommonSubstring = table[i+1][j+1];
}
} else {
table[i+1][j+1] = 0;
}
}
}
return longestCommonSubstring;
}