Develop Reference

Javascript Random Name Guesser: Unresponsive Script Issues

This is my first post here and I am having trouble wording a question, so please bear with me as I have been on this issue for hours.
My friend and I have thought of a fun little function that is supposed to guess the user's name (through an <input> tag) in a certain amount of trials using the random number function to access string letters from an alphabet array numbered 0-25. The function is also supposed to give the user the number of trials it took to guess their name.
I keep getting a non-responsive script, (line 33 - The line containing the second "for loop").
var goal = document.getElementById("your_Name").value;
var 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"];
var goalArray = goal.split("");
var trials = 0;
var guessArray = new Array();
var i;
var n;
for (i = 0; i < goalArray.length; i++){
guessArray.push(alphabet[Math.floor(Math.random()*26)]);
}
while (goalArray != guessArray){
trials++;
guessArray = [];
for (n = 0; n < goalArray.length; n++){
guessArray.push(alphabet[Math.floor(Math.random()*26)]);
}
}
document.getElementById("appendomatic").innerHTML = "It took " + guessArray + " trials to guess correctly";
Any help or attempt to help would be immensely appreciated!
In case anyone was wondering: This little idea of ours was to test the randomness of Javascript's random function through trials (he made the same program in MatLab, so we are going to compare results of the random functions from both languages).

goalArray != guessArray is always true since they are two separate arrays; even if they contain the same elements.
Since they appear to just be arrays of individual letters in a-z you could compare them with something like goalArray + '' != guessArray, because the toString() of the arrays will compare correctly.

This is how I eventually got it to work (by nesting the while loop and second for loop in another for loop):
var goal = document.getElementById("your_Name").value;
var goalArray = goal.split("");
var 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"];
var trials = 0;
var guessArray = [];
for (i = 0; i < goalArray.length; i++){
guessArray.push(alphabet[Math.floor(Math.random()*26)]);
}
for (x = 0; x < goalArray.length; x++){
while (goalArray[x] != guessArray[x]){
trials++;
guessArray = [];
for (n = 0; n < goalArray.length; n++){
guessArray.push(alphabet[Math.floor(Math.random()*26)]);
}
}
document.getElementById("appendomatic").innerHTML = "It took " + trials + " trials to guess correctly";
}
}

Javascript keep getting undefined after function - prompt

So I`m working ona simple JS code. We just started to learn about functions.
I need to make a function named "printStars".
I need to take a number from the user and accourding that number print "*".
This is what I did:
<script>
function printStars()
{
var n = Number(prompt("Insert number of stars:","0.."));
for (i = 0; i < n; i++)
{
document.write("*");
}
}
var stars = printStars();
document.write(stars);
</script>
In the end I get my result with a minus of getting "undefined".
I would love to get some help, and an explanation why is keep happening.
Thanks guys!

jsfiddle demo
function printStars(){
var n = prompt("Insert number of stars:","0..");
var stars='';
for (i = 0; i < n; i++){
stars+='*';
}
$('body').html(stars) //jsfiddle does not allow document.write()
//document.write(stars);
}
//call the function
printStars();

You don't need this
document.write(stars);
You just need this:
// This will make you function to be evaluated and
// the code in your function will be executed.
printStars();
function printStars()
{
var n = Number(prompt("Insert number of stars:","0.."));
for (i = 0; i < n; i++)
{
document.write("*");
}
}
printStars();

Javascript: Example of recursive function using for loops and substring - can't figure out where I'm going wrong

I'm currently working on coderbyte's medium challenge entitled "Permutation Step."
The goal is to take user input, num, and to return the next number greater than num using the same digits So, for example, if user input is 123, then the number 132 should be returned. If user input is 12453, then 12534 should be returned...
Anywho, I have a correct model answer created by someone (probably a genius, cuz this stuff is pretty hard) and I'm trying to figure out how the answer works, line for line by having an example play out (I'm keeping it simple and playing out the function with user input 123).
The answer has 2 functions, but the 1st function used is what I'm currently trying to work out...
The relevant code is:
var PermutationStep1 = function(num) {
var num1 = num.toString();
var ar = [];
//return num1;
if (num1.length < 2) {
return num;
} else {
for(var i = 0; i < num1.length; i++) {
var num2 = num1[i];
var num3 = num1.substr(0,i) + num1.substr(i+1, num1.length -1);
var numAr = PermutationStep1(num3);
for(var j = 0; j < numAr.length; j++) {
ar.push(numAr[j] + num2);
}
}
ar.sort(function(a,b) {return a-b});
return ar;
}
}
Again, I'm trying to work thru this function with the inputted num as 123 (num = 123).
I'm pretty sure that this function should output an array with multiple elements, because the 2nd function merely compares those array elements with the original user input (in our case, 123), and returns the next greatest value.
So in our case, we should probably get an array, named 'ar', returned with a host of 3 digit values. But for some reason, I'm getting an array of 2 digit values. I can't seem to isolate my mistake and where I'm going wrong. Any help with where, specifically, I'm going wrong (whether it be the recursion, the use of substring-method, or the concating of strings together, whatever my problem may be) would be appreciated...
Here's some of my work so far:
PS1(123) / num1 = 123
i = 0;
num2 = (num1[i]) = '1';
num3 = (num1.substr(0, 0) + num1.substr(1, 2)) = ('0' + '23') = '23'
PS1(23)
i = 0;
num2 = '2';
num3 = '3'
PS1(3) -> numAr = 3 (since num1 is less than 2 digits, which is the recursion base case?)
(So take 3 into the 2nd for loop)...
ar.push(numAr[j] + num2) = ar.push('3' + '1') = 31
ar = [31] at this point
And then I go through the initial for-loop a couple more times, where i = 1 and then i = 2, and I eventually get....
ar = [31, 32, 33]...
But I'm thinking I should have something like ar = [131, 132, 133]? I'm not sure where I'm going wrong so please help. Because the answer is correctly spit out by this function, the correct answer being 132.
Note: if you need the 2nd part of the model answer (i.e. the 2nd function), here it is:
var arr = [];
function PermutationStep(num1) {
arr.push(PermutationStep1(num1));
var arrStr = arr.toString();
var arrStrSpl = arrStr.split(",");
//return arrStrSpl;
for(var p = 0; p < arrStrSpl.length; p++) {
if(arrStrSpl[p] > num1) {
return arrStrSpl[p];
}
}
return -1;
}

I'm sorry the first function i posted was under a mathematical logical mistake and i was to overhasty
I thought about it again and now i have the following function which definitley works
function getNextNumber (num)
{
var numberStr=num.toString (), l=numberStr.length, i;
var digits=new Array (), lighterDigits, digitAtWeight;
var weight,lightWeight, lighterDigits_l, value=0;
for (i=l-1;i>-1;i--)
digits.push (parseInt(numberStr.charAt(i)));
lighterDigits=new Array ();
lighterDigits.push (digits[0]);
for (weight=1;weight<l;weight++)
{
digitAtWeight=digits[weight];
lighterDigits_l=lighterDigits.length;
for (lightWeight=0;lightWeight<lighterDigits_l;lightWeight++)
{
if (digitAtWeight<lighterDigits[lightWeight])
{
lighterDigits.unshift (lighterDigits.splice (lightWeight,1,digitAtWeight)[0]);
lighterDigits.reverse ();
digits=lighterDigits.concat (digits.slice (weight+1,l));
for (weight=0;weight>l;weight++)
value+=Math.pow (10,weight)*digits[weight];
return value;
}
}
lighterDigits.push (digitAtWeight);
}
return NaN;
}

okay here is my solution i found it in 20 minutes ;)
//---- num should be a Number Object and not a String
function getNextNumber (num)
{
var numberStr=num.toString (), l=numberStr.length, i;
var digits=new Array (), digitA, digitB;
var weight,lightWeight;
var valueDifference,biggerValue;
for (i=l-1;i>-1;i--)
digits.push (parseInt(numberStr.charAt(i))); // 345 becomes a0=5 a1=4 a2=3 and we can say that num= a0*10^0+ a1*10^1+ a2*10^2, so the index becomes the decimal weight
for (weight=1;weight<l;weight++)
{
digitA=digits[weight];
biggerValue=new Array ();
for (lightWeight=weight-1;lightWeight>-1;lightWeight--)
{
digitB=digits[lightWeight];
if (digitB==digitA) continue;
valueDifference=(digitA-digitB)*(-Math.pow(10,weight)+Math.pow (10,lightWeight));
if (valueDifference>0) biggerValue.push(valueDifference);
}
if (biggerValue.length>0)
{
biggerValue.sort();
return (biggerValue[0]+num);
}
}
}

this is the solution I figured out for the problem without using a recursive function. It's passed all the tests on coderbyte. I am still new to this so using recursion is not the first thing I look for. hope this can help anyone else looking for a solution.
function PermutationStep(num) {
var numArr = (num + '').split('').sort().reverse();
var numJoin = numArr.join('');
for (var i = (num + 1); i <= parseInt(numJoin); i++){
var aaa = (i + '').split('').sort().reverse();
if (aaa.join('') == numJoin){
return i;
}
}
return -1;
}

calculating average using for loop in javascript

function averageCalculator (numvalues) {
for(i=0, i <= numvalues, i++>) {
var score = prompt("input the score")
result1 += score;
}
alert(result1 / 3);
}
this function is later triggered by a button with onclick="averageCalculator (2)
<input type="button" value="Click for the average" onclick="averageCalculator (2)">
any ideas why its not working? it should prompt you for 2 values and then alert you with the average. not sure whats wrong.

Your code has multiple issues. The for loop is not well formatted and you need to terminate statements with a semi-colon. Also you need to declare variables. And your loop will run numvalues+1 times which is why i removed the = in your loop. Also if you want to calculate an average you want to divide by numvalues.
function averageCalculator (numvalues) {
var result1 = 0;
for(i=0; i < numvalues; i++) {
var score = prompt("input the score");
result1 += score;
}
alert(result1 / numvalues);
}
On top of the invalid syntax you will run into a common "problem" with javascript here. The inputs are treated as strings and instead of being added they will be concatenated. Providing 2 and 2 as scores will result in 11. 2 concatenated with 2 = 22 / 2 = 11. You need to cast the value to a number explicitly before adding them together:
function averageCalculator (numvalues) {
var result1 = 0;
for(i=0; i < numvalues; i++) {
var score = prompt("input the score");
result1 += Number(score);
}
alert(result1 / numvalues);
}
Above code will correctly return 2

The syntax of your for-loop is wrong:
for(i=0, i <= numvalues, i++>) {
should be
for(i=0; i <= numvalues; i++) {
Tip: Also, it's better to use
for(var i=0; i <= numvalues; i++) {
since then i will be a local variable instead of a global one.

Try like this
for(var i=0; i <= numvalues; i++){}

An alternative solution (using a functional programming libary, like Underscore.js):
function averageCalculator(numValues) {
var numbers = _.map(_.range(numValues), function(element) {
return +prompt('input the score');
});
var result = _.reduce(numbers, function(memo, number) {
return memo + number;
}, memo);
alert(result / 3);
}
While a little bit more complicated (and less efficient), you'll get rid of loops altogether.
EDIT
The +prompt('input the score') does effectivly the same as Number(prompt('input the score')).

Javascript variable stays undefined

I have a problem with this script, something is going wrong.
Rnumer stays undefined.This script should return and write all uneven digits from the random number list. Can someone tell me what I do wrong. Thanks in advance
var Rnumber = new Array();
for (i = 0; i<= 100;i++)
{
Rnumber[i] = Math.ceil(Math.random()*101);
// document.write(Rnumber[i] + "<br/>");
}
function unevenAndDivisible(Rnumber)
{
var remainder = new Array();
for (i = 0; i<= 100; i++)
{
remainder = parseInt(Rnumber[i])%2;
}
return remainder;
}
document.write(unevenAndDivisible());
Changed to
var Rnumber = new Array();
for (i = 0; i<= 100;i++)
{
Rnumber[i] = Math.ceil(Math.random()*101);
// document.write(Rnumber[i] + "<br/>");
}
function unevenAndDivisible(Rnumber)
{
var remainder = new Array();
for (i = 0; i<= 100; i++)
{
remainder[i] = Rnumber[i]%2;
}
return remainder;
}
document.write(unevenAndDivisible(Rnumber));
but now i get the result :
0,1,0,0,1,0,0,0,1,1,0,0,1,0,1,1,1....
I simply want maybe I asked it wrong the first time, to write al uneven numbers from the random list of Rnumbers
Then I need to divide that through 7 and return that.
EDIT
Allmost all problems are clear , thanks everyone for that.
Their is still one question left:
In this code below it only take the first uneven value from remainder and I want that it takes all values that are uneven to the next if statement to check %7.
Maybe you see the problem better if you run it for youreself
var Rnumber = new Array();
for (i = 0; i<= 100;i++)
{
Rnumber[i] = Math.ceil(Math.random()*101);
}
function unevenAndDivisible()
{
var remainder = [];
var answer = [];
for (i = 0; i<= 100; i++)
{
if (Rnumber[i]%2 !== 0)
{
remainder.push(Rnumber[i]);
for (c = 0; c <= remainder.length;c++)
{
if (remainder[c]%7 == 0)
{
answer.push(remainder[c]);
}
}
}
}
return answer;
}
answer = unevenAndDivisible();
document.write(answer);
Problem solved , Thanks everyone

You don't need to pass Rnumber to the function, as it's already available in scope:
function unevenAndDivisible()
{
var remainder = [];
for (i = 0; i<= 100; i++)
{
if (Rnumber[i]%2 !== 0) {
remainder.push(Rnumber[i]);
}
}
return remainder;
}
remainder = unevenAndDivisible();
console.log(remainder);
JS Fiddle demo.
Edited in response to question from OP (in comments to question, above):
...can someone explain what this mean: var remainder = [];
Sure, it's array-literal notation, which is equal to: var remainder = new Array();, it's just a little more concise, and I prefer to save myself the typing. I get the impression, from JS Lint, whenever I use var x = new Array(); therein that the above version is generally preferred (since it complains otherwise), but I don't know why.

Either pass Rnumber to the function unevenAndDivisible or omit it from the argument list. Since it is an argument, it has more local scope than the initial declaration of Rnumber.

Your problem is the line
function unevenAndDivisible(Rnumber)
You are passing in Rnumber in as an argument, but when you call unevenAndDivisible()
you are not passing it it.
Consequently for the body of the function Rnumber is undefined (cause you passed nothing in)
The following snippet is equivalent to what you wrote nad might explain better
function unevenAndDivisible(xyz)
{
var remainder = new Array();
for (i = 0; i<= 100; i++)
{
remainder = parseInt(xyz[i])%2;
}
return remainder;
}
then called as
unevenAndDivisible(undefined)
to fix it remove the argument from the call definition
i.e. define it as
function unevenAndDivisible()

1 - you is not defining the Rnumber value that's function argument.
2 - in loop, you're defining remainder to divised value of ranumber and is not saving in array; try:
change:
remainder = parseInt(Rnumber[i])%2;
to
remainder[i] = parseInt(Rnumber[i])%2;

var array = [],
i = 100;
while (i--) {
var random = Math.random()*i|0;
if(random % 2)
array.unshift(random);
}
alert(array);