Develop Reference

Converting nested loops into forEach();

Im trying to learn forEach() method but i cant find more advanced examples. So i thought about refactoring my Codewars code to learn from it. I dont know know to properly use forEach method in nested loops. Hope You can help me learn from this example :)
6 kyu - Replace With Alphabet Position
https://www.codewars.com/kata/546f922b54af40e1e90001da/train/javascript
function alphabetPosition(text) {
let textToArray = text.replace(/[^a-zA-Z]/gi,'').toUpperCase().split(''); //Eliminate anything thats not a letter
const alphabet = ["A","B","C","D","E","F","G","H","I","J","K","L","M","N","O","P","Q","R","S","T","U","V","W","X","Y","Z"];
let pointsHolder = []; //empty array for score
for (let i = 0; i < textToArray.length; i++){
for (let j = 0; j < alphabet.length; j++) {
if (textToArray[i] == alphabet[j] ) { //We check the index of given string letter in alphabet
pointsHolder.push(j+1) //give it a score based on place in alphabet(+1 for 0 as 1st index)
}
}
}
return pointsHolder.join(' '); //return scored array as a string with spaces
}

There is really no need to use a nested loop, which is computationally expensive. With that, you also don't have to manually create an A-Z array.
You can easily convert alphabets to any arbitrary number using String.charCodeAt(). a has a character code of 97, b has a character code of 98, and etc... to get a one-based index (a=1, b=2, ...) you jus t need to subtract 96 from the number.
function alphabetPosition(text) {
const alphabets = text.toLowerCase().replace(/[^a-z]/g, '').split('');
return alphabets.map(alphabet => alphabet.charCodeAt(0) - 96).join(' ');
}
Alternatively you can also use a for...of loop, but that requires storing the array in yet another variable before returning it:
function alphabetPosition(text) {
const alphabets = text.toLowerCase().replace(/[^a-z]/g, '');
const codes = [];
for (const alphabet of alphabets) {
codes.push(alphabet.charCodeAt() - 96);
}
return codes.join(' ');
}

(Note: #Terry's solution is still the more efficient solution to your code challenge)
You can replace it in the following way:
function alphabetPosition(text) {
let textToArray = text.replace(/[^a-zA-Z]/gi, '').toUpperCase().split('');
const alphabet = ["A", "B", "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M", "N", "O", "P", "Q", "R", "S", "T", "U", "V", "W", "X", "Y", "Z"];
let pointsHolder = [];
textToArray.forEach(t2a => {
alphabet.forEach((a, j) => {
if (t2a == a) { pointsHolder.push(j + 1) }
})
})
return pointsHolder.join(' ');
}
console.log(alphabetPosition("ABCSTU"))

An alternative to the charCode solution proposed in Terry's answer but which also avoids nested loops is be to create a Map of the characters you want to score against and then access it per character from the passed string.
Keep in mind that strings are iterable without needing to convert to an array.
function alphabetPosition(text) {
text = text.toUpperCase().replace(/[^A-Z]/gi, '');
const alphabet = new Map(
["A", "B", "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M", "N", "O", "P", "Q", "R", "S", "T", "U", "V", "W", "X", "Y", "Z"]
.map((v, i) => [v, i + 1])
);
const pointsHolder = [];
for (const char of text) {
pointsHolder.push(alphabet.get(char))
}
return pointsHolder.join(' ');
}
console.log(alphabetPosition("AB😬CS🐹TU"))
This also allows you to use a Map which doesn't necessarily have consecutive charCodes
function alphabetPosition(text) {
text = text.toUpperCase().replace(/[^😬🐹🤓]/gi, '');
const alphabet = new Map(
["😬", "🐹", "🤓"]
.map((v, i) => [v, i + 1])
);
const pointsHolder = [];
for (const char of text) {
pointsHolder.push(alphabet.get(char))
}
return pointsHolder.join(' ');
}
console.log(alphabetPosition("AB😬CS🐹TU"))

Checking values of one array against another in JS

I'm trying to do a check that the first array contains the same values of the second array.
However I'm confused about my code.
First question is: why is my code running my else statement if all letters in the first array are contained in the second? it will run 2 lines of "this is not valid"
Second question is: if my first array contains a duplicate letter it will still pass the check e.g
["a", "b" , "a", "d", "e", "f"]; even though there is two a's in the first it will see the same "a" again. Anyone know a way around this.
Sorry for my long winded questions but I hope it makes sense. Thanks :)
var letters = ["a", "b" , "c", "d", "e", "f"];
var otherLetters = ["a","b", "c" , "d", "e", "f"];
var i = -1;
while(i<=letters.length){
i++;
if(otherLetters.includes(letters[i])){
console.log("This is valid");
}
else
console.log("This is not valid");
}

You didn't close the brackets. And your loop is very confusing, please use foreach. Here is a working example:
const letters = ["a", "b" , "c", "d", "e", "f"];
const otherLetters = ["a","b", "c" , "d", "e", "f"];
letters.forEach(el => {
if (otherLetters.includes(el)) {
console.log(el + 'is valid');
} else {
console.log(el + 'is not valid');
}
});

You are trying to access array elements which are out of bounds. The script runs 8 iterations over an array with 6 elements.

Nothing to worry, cpog90.
Try this solution.
var letters = ["a", "b" , "c", "d", "e", "f"];
var otherLetters = ["a","b", "c" , "d", "e", "f"];
var i = 0;
while(i<letters.length){
if(otherLetters.includes(letters[i])){
console.log("This is valid");
}
else {
console.log("This is not valid "+i);
}
i++;
}
What went wrong in your logic?
If you declare i = -1 and while(i<=letters.length), As 6 is length of letters, 8 iterations will be done as follows.
For first iteration (i = -1), 'while' condition returns true and checks for 'a'
output: This is valid
For second iteration (i = 0), 'while' condition returns true and checks for 'b'
output: This is valid
For third iteration (i = 1), 'while' condition returns true and checks for 'c'
output: This is valid
For fourth iteration (i = 2), 'while' condition returns true and checks for 'd'
output: This is valid
For fifth iteration (i = 3), 'while' condition returns true and checks for 'e'
output: This is valid
For sixth iteration (i = 4), 'while' condition returns true and checks for 'f'
output: This is valid
For seventh iteration (i = 5), 'while' condition returns true and checks for undefined value.
output: This is not valid
For eighth iteration (i = 6), 'while' condition returns true and checks for undefined value.
output: This is not valid

First of all you have set i = -1 which is confusing since array start position is 0.
The reason your loop is running two extra times is because loop started at -1 instead of 0 and next the condition i <= length.
Since [array length = last index + 1] your loop runs extra two times.
Just to make your code work assign var i = 0 and while condition i < letters.length

Simplest solution is using lodash. It has all optimizations out-of-the-box:
var letters = ["a", "b" , "c", "d", "e", "f"];
var otherLetters = ["f", "a","b", "c" , "d", "e"];
const finalLetters = _.sortBy(letters);
const finalOtherLetters = _.sortBy(otherLetters);
if (_.isEqual(finalLetters, finalOtherLetters)) {
console.log('Two arrays are equal.');
} else {
console.log('Two arrays are not equal.');
}
<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.15/lodash.min.js"></script>

Arrays are index based and starts from 0. So, the -1 and the less than letters.length check puts the code into out of bounds.
var letters = ["a", "b" , "c", "d", "e", "f"];
var otherLetters = ["a","b", "c" , "d", "e", "f"];
var i = 0;
while(i<letters.length)
{
if(otherLetters.includes(letters[i]))
{
console.log("This is valid");
}
else
{
console.log("This is not valid");
}
i++;
}

You can use a combination of Array.prototype.every with Array.prototype.includes, along with some extra guard clauses.
const areSequenceEqual = (arr1, arr2) => {
if (!arr1 || !arr2) {
return false;
}
if (arr1.length !== arr2.length) {
return false;
}
return arr1.every(x => arr2.includes(x));
};
const letters = ["a", "b", "c", "d", "e", "f"];
const otherLetters = ["a", "b", "c", "d", "e", "f"];
const someOtherLetters = ["a", "b", "c", "d", "e", "f", "g"];
console.log(areSequenceEqual(letters, otherLetters));
console.log(areSequenceEqual(letters, undefined));
console.log(areSequenceEqual(letters, someOtherLetters));

while loop is not working properly

I am writing code for my one of the exercises in freecodecamp.com called as Pig Latin problem. For a while loop it should stop executing the code inside it when the condition becomes wrong.For my case the while loop must stop executing the codes inside it when it finds that it seen a vowel in the charas array during iteration. I think my code is correct in my point of view, but while loop is not stopping execution when it sees a vowel instead it iterate through every element in the charas array.
Here is my code
function translatePigLatin(str) {
var vowels = ['a','e','i','o','u'];
var f="";
var charas = str.split("");
if(vowels.indexOf(charas[0])!==-1) {
// vowel
charas.push("w");
charas.push("a");
charas.push("y");
f = charas.join("");
} else {
//if first letter is a consonant or cluster of consonants
var i = 0;
while(vowels.indexOf(charas[i]) ===-1) {
charas.push(charas[i]);
charas.splice(i,1);
i = i+1;
}
charas.push('a');
charas.push('y');
f = charas.join("");
}
return f;
}
translatePigLatin("california");

It works as work cause
charas.push(charas[i]);
charas.splice(i,1);
i = i+1;
After the first iteration it move 'a' letter at the begging as result i == 1 (in second iteration) charas[i] refers to consonant 'l'.

Your problem is that you increment i. You move the first element from the start of the array and then increment i you are skipping a letter because what was charas[1] is now charas[0] and what is charas[1] was charas[2].
If you step through the code and inspect the charas array you can see this happening:
Starting state:
["c", "a", "l", "i", "f", "o", "r", "n", "i", "a"]
"c" gets moved to the end
i is incremented to 1
["a", "l", "i", "f", "o", "r", "n", "i", "a", "c"]
"l" is at position 1, so it gets moved to the end.
i is incremented to 2
["a", "i", "f", "o", "r", "n", "i", "a", "c", "l"]
"f" is at position 2, so it gets moved to the end.
i is incremented to 3
["a", "i", "o", "r", "n", "i", "a", "c", "l", "f"]
"r" is at position 3, so it gets moved to the end.
i is incremented to 4
["a", "i", "o", "n", "i", "a", "c", "l", "f", "r"]
"i" is at position 4, the while condition is met, "aioniaclfr" will be returned.
If you just get rid of i and always check charas[0] it works like expected:
function translatePigLatin(str) {
var vowels = ['a','e','i','o','u'];
var f = "";
var charas = str.split("");
if(vowels.indexOf(charas[0]) !== -1) {
// vowel
charas.push("w");
charas.push("a");
charas.push("y");
f = charas.join("");
} else {
//if first letter is a consonant or cluster of consonants
while(vowels.indexOf(charas[0]) === -1) {
charas.push(charas[0]);
charas.splice(0,1);
}
charas.push('a');
charas.push('y');
f = charas.join("");
}
return f;
}
document.getElementById('out').textContent = translatePigLatin("california");
<div id="out"></div>
As a side note, this type of while condition will lead to an infinite loop if someone passes in a string that is all consonants, it will just keep shuffling the letters around because it will never find a vowel to stop it. To avoid this, I would add another if condition to check for that to make sure it won't happen:
function translatePigLatin(str) {
var vowels = ['a','e','i','o','u'];
var f = "";
var charas = str.split("");
if (!str.match(/[aeiou]+/)) {
// only consonants do something
f = str + 'ay';
} else if (vowels.indexOf(charas[0]) !== -1) {
// vowel
charas.push("w");
charas.push("a");
charas.push("y");
f = charas.join("");
} else {
//if first letter is a consonant or cluster of consonants
while(vowels.indexOf(charas[0]) === -1) {
charas.push(charas[0]);
charas.splice(0,1);
}
charas.push('a');
charas.push('y');
f = charas.join("");
}
return f;
}
document.getElementById('out').textContent = translatePigLatin("wkrp");
<div id="out"></div>
/[aeiou]+/ is a regular expression meaning any vowel one or more times anywhere in the string the ! in !str.match(/[aeiou]+/) negates the result of match, so if there are no vowels in the string that branch of the if is followed.

You haven't added the condition to exit the while loop, use i <= length of charas. Check below snippet.
function translatePigLatin(str) {
var vowels = ['a', 'e', 'i', 'o', 'u'];
var f = "";
var charas = str.split("");
if (vowels.indexOf(charas[0]) !== -1) {
// vowel
charas.push("w", "a", "y");
f = charas.join("");
} else {
//if first letter is a consonant or cluster of consonants
var i = 0;
var len = charas.length;
while (vowels.indexOf(charas[i]) === -1 && i <= len) {
charas.push(charas[i]);
charas.splice(i, 1);
i++;
}
charas.push('a', 'y');
f = charas.join("");
}
return f;
}
console.log(translatePigLatin("california"));

The problem is that your are iterating AND modifying the same array at the same time
You can simplify your code like this
function translatePigLatin(str) {
var vowels = ['a', 'e', 'i', 'o', 'u'];
//start with vowel
if (vowels.indexOf(str[0]) !== -1) {
return str + "way";
}
var i = 0;
var beforeVowel = "";
var chars = str.split("");
while (vowels.indexOf(chars[i]) === -1 && i < str.length) {
beforeVowel += chars[i];
i++;
}
return str.substring(i) + beforeVowel + "ay";
}
console.log(translatePigLatin("california"));
console.log(translatePigLatin("pig"));
console.log(translatePigLatin("eat"));

manually sorting a paragraph by made-up alphabet with javascript

I'm trying to sort a paragraph alphabetically, not according to the normal ABC but a made-up one (var order).
I wrote this function and it works great, but only for the first letter of each word - not in-word sorting as well (for example, in correct ABC 'banana' would come before 'birthday').
I'm not sure where to go from here.
$("#send").click(function () {
var text = $("#text").val().replace(/[^A-Za-z0-9_\s]/g, "").toUpperCase().split(" ");
var order = ["Q", "B", "K", "D", "H", "V", "Z", "E", "F", "O", "G", "L", "M", "S", "N", "P", "I", "X", "A", "R", "W", "U", "C", "J", "T", "Y"];
var i, t, j;
var newText = []; // will hold the new alphabet
// function to sort the words:
for (i = 0; i < order.length; i++) {
for (t = 0; t < text.length; t++) {
var firstChar = text[t][0];
if (order[i] == firstChar) {
newText.push(text[t]);
}
}
}
console.log(newText.join(','));
});
EDIT:
An example input can be: "Hi dan don't you think that this is awesome",
and I want the output to be: "don't dan hi is awesome this think that you".

You could use an object with the index of the letters and use Array#sort with a callback which looks for every letter adn calculates the order.
function foo(text) {
var text = text.replace(/[^A-Za-z0-9_\s]/g, "").toUpperCase().split(" "),
order = "QBKDHVZEFOGLMSNPIXARWUCJTY",
ref = {};
order.split('').forEach(function (a, i) { ref[a] = i + 1; });
text.sort(function (a, b) {
var i = 0, v;
do {
v = (ref[a[i]] || 0) - (ref[b[i]] || 0);
i++;
} while (!v)
return v;
});
console.log(text.join(', '));
}
foo('a aa ab b ba bb');
foo('banana birthday');

The problem with your algorithm is that it only compares the first letter in each word, but if the letters are the same the algorithm needs to compare the next letter in each word. Here's a solution that uses recursion:
function doSort(inputArr) {
var words = inputArr.slice(0);
var alphabet = ["Q", "B", "K", "D", "H", "V", "Z", "E", "F", "O", "G", "L", "M", "S", "N", "P", "I", "X", "A", "R", "W", "U", "C", "J", "T", "Y"];
words.sort(function(item1, item2) {
return sortRecursive(item1, item2, 0);
});
function sortRecursive(item1, item2, idx) {
if (item1.length <= idx && item2.length <= idx) {
return 0;
} else if (item1.length <= idx) {
return -1;
} else if (item2.length <= idx) {
return 1;
} else if (item1[idx] == item2[idx]) {
return sortRecursive(item1, item2, idx+1);
} else {
return alphabet.indexOf(item1[idx].toUpperCase()) - alphabet.indexOf(item2[idx].toUpperCase());
}
}
return words;
}
var arr = ["banana", "quebec", "bird", "birthday", "birdman", "bird"];
var sortedArr = doSort(arr);
console.log('unsorted',arr);
console.log('sorted', sortedArr);
https://jsfiddle.net/2qgaaozo/

Google Spreadsheets Script Keeps Writing Empty Strings

I have a Google form that gets submitted to a Google spreadsheet. On the spreadsheet side, I have a Google Apps Script that is supposed to encrypt the submitted password. But for whatever reason, it writes an empty string to where the encrypted password should be. This is really starting to stress my out. Here is my code:
function encryptPassword(e) {
var password = e.values[6];
var split = password.split("");
password = "";
var char;
for(char in split) {
password = password.concat(getBinary(split[char]));
}
var spreadsheet = SpreadsheetApp.openById("1CywforbyBmPDHt2Uw9lJtyhqeklAAJp0IG7GfVV6U5U");
spreadsheet.getRange("G" + spreadsheet.getLastRow().toString()).setValue(password);
spreadsheet.getRange("H" + spreadsheet.getLastRow().toString()).setValue(password);
}
function getBinary(char) {
var binary = "";
var numValue;
var range;
var value;
var chars = [
["#", "A", "B", "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M", "N", "O", "P"],
["#", "Q", "R", "S", "T", "U", "V", "W", "X", "Y", "Z"],
["&", "a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "l", "m", "n", "o", "p"],
["%", "q", "r", "s", "t", "u", "v", "w", "x", "y", "z"],
["$", "0", "1", "2", "3", "4", "5", "6", "7", "8", "9"]
];
for(range in chars) {
for(value in range) {
if(value > 0) {
if(char == chars[range][value]) {
numValue = value - 1;
binary = binary + chars[range][0];
if(numValue / 8 >= 1) {
numValue = numValue - 8;
binary = binary.concat("1");
} else {
binary = binary.concat("0");
}
if(numValue / 4 >= 1) {
numValue = numValue - 4;
binary = binary.concat("1");
} else {
binary = binary.concat("0");
}
if(numValue / 2 >= 1) {
numValue = numValue - 2;
binary = binary.concat("1");
} else {
binary = binary.concat("0");
}
if(numValue / 1 >= 1) {
binary = binary.concat("1");
} else {
binary = binary.concat("0");
}
}
}
}
}
return binary;
}
The encryptPassword(e) function is set to run whenever a form is submitted to the spreadsheet. Also please be aware that I have modified the contents of the chars array in an attempt to keep my encryption private. This shouldn't make a difference though since the rest of the code stays the same.
How do I fix my script so it actually writes an encrypted password to the spreadsheet rather than an empty string?

You've got two For/In loops:
for(range in chars) {
for(value in range) {
A For/In loop is meant to loop through the properties of an object. When you use it to loop through an array, like you are doing, the "property" is the index number of the array.
So the line:
for(range in chars) {
Is causing the variable range to be a number value on every loop. On the first loop, the value of range is zero.
The second loop:
for(value in range) {
is never looping. There is nothing to loop through. The value of the variable range is just a single number. You can't loop through a single number. If you use the debugger, you can watch what every line is doing, and execute one line of code at a time.
If you want to get the index position of one of the characters in the password, you could use indexOf(). For example, if the character in the password was the letter "i".
var indexPosition = chars[2].indexOf(char);
The value of indexPosition would be 9. The third array in the outer array chars has an element "i" in the 9th index position.