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How do I input values for this function and output the power(of input values)

Code snippet:
Question: returns "undefined" on browser console,how do I get the code to input a and b and output power?
var a = 0;
var b = 0;
function power(a,b)
{
if (b === 0) {
console.log("power = 1");
} else if (b === 1) {
console.log("power = a");
} else {
return math.power(a, b-1);
}
console.log("Power");
}

did you call your function with required values? i.e
power(a,b);

var a = 0;
var b = 0;
function power(a,b)
{
if (b === 0) {
console.log("power = 1");
} else if (b === 1) {
console.log("power = a");
} else {
return math.power(a, b-1);
}
console.log("Power");
}
//call function
power(a,b);

Replace text in an <li> tag in an ul

I'm new to web programming, and I'm trying to complete a simple guessing game project.
Right now I'm stuck because I'm trying to update an unordered list with the player's past guesses, but the page does not update.
Here is my jQuery code:
$(document).ready(function() {
game = new Game;
var guessNum
onSubmit = function(event){
event.preventDefault();
var input = $('#player-input');
var guess = +input.val();
input.val('');
var result = game.playersGuessSubmission(guess);
if (result == 'You have already guessed that number.') {
$('#title').text(result);
} else if (result === 'You Win!' || result === 'You lose.') {
$('#title').text(result);
$('#subtitle').text('Press the reset button to play again.')
$('#hint').prop('disabled', true)
$('#submit').prop('disabled', true)
} else { //this is the relevant portion
guessNum = (game.pastGuesses.length - 1).toString();
$('#' + guessNum).text(guessNum);
}
};
$('#submit').on('click', function(e){
onSubmit(e);
});
$('#player-input').on('keypress', function(e) {
if(e.which == 13) {
e.preventDefault();
onSubmit(e);
};
});
});
Here is the unordered list's html:
<div id='guesses'>
<!-- unordered list of guesses -->
<ul id='past-guesses' class="list-inline center">
<li id='0' class="guess list-group-item ">-</li>
<li id='1'class="guess list-group-item">-</li>
<li id='2' class="guess list-group-item">-</li>
<li id='3' class="guess list-group-item">-</li>
<li id='4' class="guess list-group-item">-</li>
</ul>
</div>
I have also tried not using the identifiers in the html, and instead selecting the li elements this way:
var idStr = "#past-guesses:eq(" + guessNum + ")"
$(idStr).text(game.playersGuess.toString());
In either case, the page does not update with the new values in the unordered list displayed. What am I doing wrong?
EDIT
In response to the request in comments, here's my entire JS file (now slightly edited because I was experimenting with changing the list id's to not begin with a number):
function generateWinningNumber() {
num = Math.random()
if (num === 0) {
return 1;
} else {
roundNum = Math.floor(num*100);
return roundNum + 1;
}
}
function shuffle(array) {
var m = array.length, t, i;
// While there remain elements to shuffle…
while (m) {
// Pick a remaining element…
i = Math.floor(Math.random() * m--);
// And swap it with the current element.
t = array[m];
array[m] = array[i];
array[i] = t;
}
return array;
}
function Game(){
this.winningNumber = generateWinningNumber();
this.playersGuess = null;
this.pastGuesses = [];
}
Game.prototype.difference = function() {
return Math.abs(this.playersGuess - this.winningNumber);
}
Game.prototype.isLower = function() {
if (this.playersGuess < this.winningNumber) {
return true;
} else {
return false;
}
}
Game.prototype.checkGuess = function() {
if (this.playersGuess === this.winningNumber) {
return "You Win!";
}
if (this.pastGuesses.indexOf(this.playersGuess) > -1) {
return "You have already guessed that number.";
}
this.pastGuesses.push(this.playersGuess);
if (this.pastGuesses.length >= 5) {
return "You Lose.";
} else if (this.difference() < 10) {
return "You're burning up!";
} else if (this.difference() < 25) {
return "You're lukewarm.";
} else if (this.difference() < 50) {
return "You're a bit chilly.";
} else {
return "You're ice cold!";
}
}
Game.prototype.playersGuessSubmission = function(num) {
if (num < 1 || num > 100 || typeof num != 'number') {
throw "That is an invalid guess."
} else {
this.playersGuess = num;
return this.checkGuess();
}
}
Game.prototype.provideHint = function() {
return shuffle([generateWinningNumber(), generateWinningNumber(), this.winningNumber]);
}
newGame = function() {
game = new Game;
return game;
}
$(document).ready(function() {
var game = new Game;
var guessNum
onSubmit = function(event){
event.preventDefault();
var input = $('#player-input');
var guess = +input.val();
input.val('');
var result = game.playersGuessSubmission(guess);
if (result == 'You have already guessed that number.') {
$('#title').text(result);
} else if (result === 'You Win!' || result === 'You lose.') {
$('#title').text(result);
$('#subtitle').text('Press the reset button to play again.')
$('#hint').prop('disabled', true)
$('#submit').prop('disabled', true)
} else {
guessNum = (game.pastGuesses.length - 1).toString();
$('#l' + guessNum).text(guessNum);
}
};
$('#submit').on('click', function(e){
onSubmit(e);
});
$('#player-input').on('keypress', function(e) {
if(e.which == 13) {
e.preventDefault();
onSubmit(e);
};
});
});
});

You need to escape the CSS selector.
try to replace this line:
$('#' + guessNum).text(guessNum);
with this:
var selector = "#\\" + guessNum.toString().charCodeAt(0).toString(16) + " " + guessNum.toString().substr(1);
$(selector).text(guessNum);
you can read more at:
https://www.w3.org/International/questions/qa-escapes

what is wrong with .this. javascript if else code?

it works if i use the first half only but i need to widen the parameters
//document.querySelectorAll('font[color="black"]');
var fonts = document.querySelectorAll('font[color="black"]');
var searchString = 'Mir';
var searchString2 = 'MirrorCreator';
for (var i = 0; i < fonts.length; i++) {
var font = fonts[i];
if (fonts[i].innerHTML.indexOf(searchString) !== - 1) {
//alert('Match');
var eventLink = 'ComeHere';
var elA = document.createElement('a');
elA.setAttribute('id', eventLink);
elA.setAttribute('name', eventLink);
font.appendChild(elA);
window.location.hash = 'ComeHere';
break;
}
else (fonts[i].innerHTML.indexOf(searchString2) !== - 1) {
//alert('Match');
var eventLink2 = 'ComeHere2';
var elA2 = document.createElement('a');
elA2.setAttribute('id', eventLink2);
elA2.setAttribute('name', eventLink2);
font.appendChild(elA2);
window.location.hash = 'ComeHere2';
break;
}
}

Here you have wrong syntax:
else (fonts[i].innerHTML.indexOf(searchString2) !== - 1) {
It should be simple
else {
or
else if (fonts[i].innerHTML.indexOf(searchString2) !== - 1) {

You need to change your if else statement.
if(// conditional)
{
// do something.
}
else if(// conditional){
// do something....
}

Your else needs to be else if, because else isn't expecting (fonts[i].innerHTML.indexOf(searchString2) !== - 1)

Edit ajax loaded content

I have a HTML that loads a table from another page. I've got the CSS to work properly, but I can't edit the table using jQuery when it's pooled by the script, only when I have the table directly on the page. I'm guessing that maybe my changes are running before the load? I don't know..
I want to let you know that I'm not a programmer my self, but more of a curious person. I've searched around and found some things, but the lack of knowledge doesn't let me implement them. Hope you can help me.
The Script I use to read the data from the other page (p1.html)
<script type="text/javascript">
var TimerLoad, TimerChange;
var MaxNum, Rafraichir, Changement, ClassementReduit, ClassementReduitXpremier;
var UrlRefresh, UrlChange;
Rafraichir = 30000;
Changement = 150000;
MaxNum = 1;
ClassementReduit = 0;
ClassementReduitXpremier = 10;
function Load(url, target) {
var xhr;
var fct;
if (UrlChange) url = UrlRefresh;
else UrlRefresh = url;
UrlChange = 0;
if (TimerLoad) clearTimeout(TimerLoad);
try {
xhr = new ActiveXObject("Msxml2.XMLHTTP")
} catch (e) {
try {
xhr = new ActiveXObject("Microsoft.XMLHTTP")
} catch (e2) {
try {
xhr = new XMLHttpRequest
} catch (e3) {
xhr = false
}
}
}
xhr.onreadystatechange = function() {
if (xhr.readyState == 4 && xhr.status == 200)
if (ClassementReduit == 0) document.getElementById(target).innerHTML = xhr.responseText;
else document.getElementById(target).innerHTML = ExtraireClassementReduit(xhr.responseText)
};
xhr.open("GET", url + "?r=" + Math.random(), true);
xhr.send(null);
fct = function() {
Load(url, target)
};
TimerLoad = setTimeout(fct, Rafraichir)
}
function ExtraireClassementReduit(Texte) {
var i, j, CompteurTD, CompteurTR;
var ColPosition, ColNumero, ColNom, ColEcart1er;
var Lignes;
var NouveauTexte;
CompteurTR = 0;
ColPosition = -1;
ColNumero = -1;
ColNom = -1;
ColEcart1er = -1;
Texte = Texte.substring(Texte.indexOf("<tr"));
Lignes = Texte.split("\r\n");
NouveauTexte = '<table width="100%" cellpadding="0" cellspacing="0">';
for (i = 0; i < Lignes.length; i++)
if (Lignes[i].substring(0, 3) == "<tr") {
NouveauTexte += Lignes[i];
CompteurTD = 0
} else if (Lignes[i].substring(0, 4) == "</tr") {
CompteurTR++;
if (CompteurTR == ClassementReduitXpremier + 1) break
} else if (Lignes[i].substring(0, 3) == "<td") {
if (CompteurTR == 0)
if (Lignes[i].indexOf("\"Id_Position\"") != -1) {
ColPosition = CompteurTD;
NouveauTexte += Lignes[i].replace(/ width=".*"/i, "")
} else if (Lignes[i].indexOf("\"Id_Numero\"") != -1) {
ColNumero = CompteurTD;
NouveauTexte += Lignes[i].replace(/ width=".*"/i, "")
} else if (Lignes[i].indexOf("\"Id_Nom\"") != -1) {
ColNom = CompteurTD;
NouveauTexte += Lignes[i].replace(/ width=".*"/i, "")
} else {
if (Lignes[i].indexOf("\"Id_Ecart1er\"") != -1) {
ColEcart1er = CompteurTD;
NouveauTexte += Lignes[i].replace(/ width=".*"/i, "")
}
} else if (CompteurTD == ColPosition || CompteurTD == ColNumero || CompteurTD == ColNom || CompteurTD == ColEcart1er) NouveauTexte += Lignes[i];
CompteurTD++
}
NouveauTexte += "</table>";
return NouveauTexte
}
function Change() {
var Num, Index;
if (document.forms["Changement"].chkChangement.checked) {
Index = UrlRefresh.indexOf(".");
Num = parseInt(UrlRefresh.substring(1, Index)) + 1;
if (Num > MaxNum) Num = 1;
UrlRefresh = "p" + Num + ".html";
UrlChange = 1;
fct = function() {
Change()
};
TimerChange = setTimeout(fct, Changement)
} else if (TimerChange) clearTimeout(TimerChange)
};
</script>
Loading the table into the body
$(document).ready(Load('p1.html', 'result'));
The code I need to run after (it works with the table directly on page or even on a button, but I can't get to work on page load)
function show_hide_column(col_id, do_show) {
var stl;
if (do_show) stl = 'block'
else stl = 'none';
var tbl = document.getElementsByTagName('table')[0];
var index = document.getElementById(col_id).cellIndex;
var rows = tbl.getElementsByTagName('tr');
for (var row = 0; row < rows.length; row++) {
var cels = rows[row].getElementsByTagName('td')
cels[index].style.display = stl;
}
}
function hide() {
show_hide_column("Id_Position", false);
show_hide_column("Id_Equipe", false);
show_hide_column("Id_Vehicule", false);
}

I fired a console.log() message for every stage of the previous code, to know when exactly the table was added to the page, to then hide the columns. Got it to work.

curious css setting issue using setInterval

I'm trying to make a palindrome checker that changes the currently compared letters as it recurs.
Essentially, callback will do:
r aceca r
r a cec a r
ra c e c ar
rac e car
My JS Bin shows that the compared letters change green sometimes, but if you run it again, the letters won't change. Why is there a difference in results? It seems to sometimes run in Chrome, more often in FireFox, but it's all intermittent.
Code if needed (also available in JS Bin):
var myInterval = null;
var container = [];
var i, j;
var set = false;
var firstLetter, lastLetter;
$(document).ready(function(){
$("#textBox").focus();
$(document).click(function() {
$("#textBox").focus();
});
});
function pal (input) {
var str = input.replace(/\s/g, '');
var str2 = str.replace(/\W/g, '');
if (checkPal(str2, 0, str2.length-1)) {
$("#textBox").css({"color" : "green"});
$("#response").html(input + " is a palindrome");
$("#palindromeRun").html(input);
$("#palindromeRun").lettering();
if (set === false) {
callback(str2);
set = true;
}
}
else {
$("#textBox").css({"color" : "red"});
$("#response").html(input + " is not a palindrome");
}
if (input.length <= 0) {
$("#response").html("");
$("#textBox").css({"color" : "black"});
}
}
function checkPal (input, i, j) {
if (input.length <= 1) {
return false;
}
if (i === j || ((j-i) == 1 && input.charAt(i) === input.charAt(j))) {
return true;
}
else {
if (input.charAt(i).toLowerCase() === input.charAt(j).toLowerCase()) {
return checkPal(input, ++i, --j);
}
else {
return false;
}
}
}
function callback(input) {
$("#palindromeRun span").each(function (i, v) {
container.push(v);
});
i = 0;
j = container.length - 1;
myInterval = setInterval(function () {
if (i === j || ((j-i) === 1 && input.charAt(i) === input.charAt(j))) {
set = false;
window.clearInterval(myInterval);
container = [];
}
console.log(i + ' : ' + j);
$(container[i]).css({"color": "green"});
$(container[j]).css({"color": "green"});
i++;
j--;
}, 1000);
}
HTML:
<input type="text" id="textBox" onkeyup="pal(this.value);" value="" />
<div id="response"></div>
<hr>
<div id="palindromeRun"></div>
I directly pasted the jsLettering code in the JSBin, but here is the CDN if needed:
<script src="http://letteringjs.com/js/jquery.lettering-0.6.1.min.js"></script>

Change:
myInterval = setInterval(function () {
if (i === j) {
set = false;
window.clearInterval(myInterval);
container = [];
}
console.log(i + ' : ' + j);
to:
myInterval = setInterval(function () {
if (i >= j) {//Changed to prevent infinite minus
set = false;
window.clearInterval(myInterval);
container = [];
}
console.log(i + ' : ' + j);
demo