Develop Reference

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);

Encryption... almost works

I wrote a simple script for a website called Codewars (here: https://www.codewars.com/kata/57814d79a56c88e3e0000786). The purpose of the function was to encrypt a string such that every second character would appear first, and then the rest of them. I tested many random strings of text; it worked for a while. But then, I tested a specific case with 17 characters: "maybe do i really", and it resulted in a character being dropped (notably a space). Initially, I thought the issue was that the .join method didn't allow a double space in a row, so I attempted to make my own function to mimic its functionality: it did not solve the problem. Could anyone answer why this specific string loses a character and returns a wrong encryption? My jsfiddle is here: https://jsfiddle.net/MCBlastoise/fwz62j2g/
Edit: I neglected to mention that it runs a certain number of times based on parameter n, encrypting the string multiple times per that value.
And my code is here:
function encrypt(text, n) {
if (n <= 0 || isNaN(n) === true || text === "" || text === null) {
return text;
}
else {
for (i = 1; i <= n; i++) {
if (i > 1) {
text = encryptedString;
}
var evenChars = [];
var oddChars = [];
for (j = 0; j < text.length; j++) {
if (j % 2 === 0) {
evenChars.push(text.charAt(j));
}
else {
oddChars.push(text.charAt(j));
}
}
var encryptedString = oddChars.join("") + evenChars.join("");
}
return encryptedString;
}
}
function decrypt(encryptedText, n) {
if (n <= 0 || encryptedText === "" || encryptedText === null) {
return encryptedText;
}
else {
for (i = 1; i <= n; i++) {
if (i > 1) {
encryptedText = decryptedString;
}
var oddChars = [];
var evenChars = [];
for (j = 0; j < encryptedText.length; j++) {
if (j < Math.floor(encryptedText.length / 2)) {
oddChars.push(encryptedText.charAt(j));
}
else {
evenChars.push(encryptedText.charAt(j));
}
}
var convertedChars = []
for (k = 0; k < evenChars.length; k++) {
convertedChars.push(evenChars[k]);
convertedChars.push(oddChars[k]);
}
var decryptedString = convertedChars.join("");
}
return decryptedString;
}
}
document.getElementById("text").innerHTML = encrypt("maybe do i really", 1);
document.getElementById("text2").innerHTML = decrypt("ab oiralmyed ely", 1)
<p id="text"></p>
<p id="text2"></p>

Nothing wrong with the code itself. Basically HTML doesn't allow 2 or more spaces. You can use <pre> tag for the case like this.
document.getElementById("text").innerHTML = "<pre>" + encrypt("maybe do i really", 1) + "</pre>";

javascript toLowerCase() function returns different string

console.log("HİNDİ".toLocaleLowerCase() == "hindi");
console.log("HİNDİ" == "hindi");
console.log("HİNDİ".toLowerCase());
console.log("HİNDİ".toLocaleLowerCase())
console.log("HİNDİ".toLowerCase())
I am building a search functionality but i come across a thing:
"HİNDİ".toLocaleLowerCase() // "hindi"
"hindi" == "HİNDİ".toLocaleLowerCase() //false
What the heck is going on here?
Solution:
#pmrotule's answer seems to work:
function to_lower(s)
{
var n = "";
for (var i = 0; i < s.length; i++) // do it for one character at a time
{
var c = s[i].toLowerCase();
// call replace() only if the character has a length > 1
// after toLowerCase()
n += c.length > 1 ? c[0].replace(/[^ -~]/g,'') : c;
}
return n;
}
Thanks,

It is a problem of string format. toLocaleLowerCase is meant for human-readable display only. However, there is still a trick you can do:
if ("hindi" == "HİNDİ".toLowerCase().replace(/[^ -~]/g,''))
{
alert("It works!");
}
EDIT
If you want to make it works with all special characters:
function to_lower(s)
{
var n = "";
for (var i = 0; i < s.length; i++) // do it for one character at a time
{
var c = s[i].toLowerCase();
// call replace() only if the character has a length > 1
// after toLowerCase()
n += c.length > 1 ? c.replace(/[^ -~]/g,'') : c;
}
return n;
}
console.log("gök" == to_lower("GÖK"));
console.log("hindi" == to_lower("HİNDİ"));
function to_low(s) // shorter version
{
var n = "";
for (var i = 0; i < s.length; i++)
{ n += s[i].toLowerCase()[0]; }
return n;
}
console.log("hindi" == to_low("HİNDİ"));

The problem is that your character İ is composed by 2 characters.
You have the I and then the 'dot' at the top (UTF-8 decimal code: 775).
Try this:
"HİNDİ".toLocaleLowerCase().split('').map((_,v)=>console.log(_.charCodeAt(0)))
Compare it with this:
"hindi".toLocaleLowerCase().split('').map((_,v)=>console.log(_.charCodeAt(0)))

Using Modulus to loop through

I've been stuck on this last part of my assignment for the longest time. I'm trying to loop through the alphabet using modulus. delta is the number of letters you have to move forward or backwards to get the real letter. SO if given getchars("H",-2), the function is supposed to return F. A problem arises however if the chars.charAt(chars.getIndexOf(data.charAt(i))) ever equals a number less than 0. I want to be able to give my function ("A", -1) or any negative number and have it return "Z".
This is an assignment for class so if possible please keep it to just modulus. I've been working on this last part for like 2 hours now.
function getChars(data,delta)
{
var chars;
var i;
var foundAt;
var newString;
chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
data = data.toUpperCase();
delta = Math.min(chars.length, delta);
i = 0;
newString = "";
while (i < data.length)
{
if(delta <= 0)
{
foundAt = (chars.indexOf(data.charAt(i)) + delta) ;window.alert(foundAt)
//newString = newString + chars.charAt(foundAt);
//i = i + 1;
}
else if((chars.indexOf(data.charAt(i)) < 0))
{
foundAt = data.charAt(i);
newString = newString + foundAt;
i = i + 1;
}
else
{
foundAt = ((chars.indexOf(data.charAt(0 + i)) + delta)) % chars.length;window.alert(foundAt);
newString = newString + chars.charAt(foundAt);window.alert(newString);
i = i + 1;
}
}
//return newString;
}

To be flexible, you can use i = chars.length - 1; and first after that do the found at.

You have to use you own modulus function :
function modulus(n,m) {
return ((n%m)+m)%m;
};
With your following code :
function getChars(data,delta)
{
var chars;
var i;
var foundAt;
var newString;
chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
data = data.toUpperCase();
i = 0;
newString = "";
while (i < data.length)
{
newString += chars.charAt(modulus(chars.indexOf(data[i])+delta,26))
i++;
}
return newString;
}

transform every 3rd letter to uppercase

how to transform every 3rd character to uppercase. for example this string pifedvcbtauzkwgnxyjrhmq converted into piFedVcbTauKkwGnxYjrHmq.
here is what i've done so far
function up3rdletter(str){
var i, result = '';
for(i = 0; i < str.length; i++){
if(i > 0 && i % 3 == 0){
result += str[i].toUpperCase();
}else{
result += str[i];
}
}
return result;
}
the script above return pifEdvCbtAuzKwgNxyJrhMq, it start converting from 4th letter. if I change the modulo number to 2 it become piFeDvCbTaUzKwGnXyJrHmQ

It's rather trivial: indexing in JS starts from 0, but you want to change letters based on 1-based index, natural for human beings. ) Solution? Either shift the remainder check:
result += i % 3 === 2 ? str[i].toUpperCase() : str[i];
... or go on checking against 0, but advance i instead:
result += (i + 1) % 3 ? str[i] : str[i].toUpperCase();
But actually, I'd probably write it as follows:
result = str.replace(/(..)(.)/g, function(_, m1, m2) {
return m1 + m2.toUpperCase();
});

function up3rdletter(str){
var i, result = '';
var counter = 1;
for(i = 0; i < str.length; i++){
if(i > 0 || counter % 3 == 0){
result += str[i].toUpperCase();
}else{
result += str[i];
}
counter++;
}
return result;
}