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Why does Javascript give me a uncaught type null error?

I'm having some trouble with my Javscript for a project (Its own document we're not allowed to use inline JS) my only that I can find while attempting to execute my program is this
"payment.js:182 Uncaught TypeError: Cannot set property 'onsubmit' of null
at init (payment.js:182)".
Now this error does not show up on JSHint when I verify my code so I don't understand how to fix it, it would be great if someone could give me some help. Heres the code:
"use strict";
//validate form inputs from payment.html
function validate() {
var errMsg = "";
var result = true; //assumes no errors
//assign elements to variables
var mastercard_check = document.getElementById("mastercard").checked;
var visa_check = document.getElementById("visa").checked;
var express_check = document.getElementById("express").checked;
var credit_name = document.getElementById("credit_name").value;
var credit_number = document.getElementById("credit_number").value;
var credit_expiry = document.getElementById("credit_expiry").value;
var credit_vv = document.getElementById("credit_vv").value;
//validations for form
if (!(mastercard_check || visa_check || express_check)) {
errMsg += "Please choose a card type\n";
result = false;
}
if (credit_name.length > 40) {
errMsg += "Please enter a name for your credit card between 1-40 characters\n";
result = false;
}
else if (!credit_name.match(/^[a-zA-Z ]+$/)) {
errMsg += "Credit card name can only contain alpha characters\n";
result = false;
}
if (isNaN(credit_number)) {
errMsg = errMsg + "Credit card number must contain digits only\n";
result = false;
}
else if (credit_number.length < 15 || credit_number.length > 16){
errMsg = errMsg + "Credit card number must contian either 15 or 16 digits\n";
result = false;
}
else {
var tempMsg = checkCardNumber(credit_number);
if (tempMsg != "") {
errMsg += tempMsg;
result = false;
}
}
if (!credit_expiry.match(/^\d{2}-\d{2}$/)) {
errMsg = errMsg + "Credit Card expiry must follow the format mm-yy\n";
result = false;
}
if (!credit_vv) {
errMsg = errMsg + "Please enter a Credit Card Verification Value\n";
result = false;
}
if (errMsg != "") {
alert(errMsg);
}
return result;
}
//obtain the credit card type
function getCardType() {
var cardType = "Unknown";
var cardArray = document.getElementById("credit_type").getElementsByTagName("input");
for(var i = 0; i < cardArray.length; i++) {
if (cardArray[i].checked) {
cardType = cardArray[i].value;
}
}
return cardType;
}
//check hte card number matches the chosen card type
function checkCardNumber(credit_number) {
var errMsg = "";
var card = getCardType();
switch(card) {
case "visa":
if (!(credit_number.length == 16)) {
errMsg = "Visa number must contian 16 digits\n";
}
else if (!credit_number.match(/^(4).*$/)) {
errMsg = "Visa number must start with a 4. \n";
}
break;
case "mastercard":
if (!(credit_number.length == 16)) {
errMsg = "Mastercard number must contian 16 digits\n";
}
else if (!credit_number.match(/^(51|52|53|54|55).*$/)) {
errMsg = "Mastercard number must start with digits 51 through 55. \n";
}
break;
case "express":
if (!(credit_number.length == 15)) {
errMsg = "American Express number must contian 15 digits\n";
}
else if (!credit_number.match(/^(34|37).*$/)) {
errMsg = "American Express number must start with 34 or 37. \n";
}
break;
}
return errMsg;
}
//calculate total cost using the meal size and quantity chosen
function calcCost(size, quantity){
var cost = 0;
if (size.search("three") != -1) cost = 100;
if (size.search("four")!= -1) cost += 150;
if (size.search("five")!= -1) cost += 200;
}
//get the stored values
function getInfo(){
var cost = 0;
if(sessionStorage.firstname != undefined){
document.getElementById("confirm_name").textContent = sessionStorage.firstname + " " + sessionStorage.lastname;
document.getElementById("confirm_address").textContent = sessionStorage.address + " " + sessionStorage.suburb + " " + sessionStorage.state + " " + sessionStorage.postcode;
document.getElementById("confirm_details").textContent = sessionStorage.email + " " + sessionStorage.phone;
document.getElementById("confirm_preferred").textContent = sessionStorage.preferred;
document.getElementById("confirm_package").textContent = sessionStorage.package;
document.getElementById("confirm_size").textContent = sessionStorage.size;
document.getElementById("confirm_quantity").textContent = sessionStorage.quantity;
cost = calcCost(sessionStorage.size, sessionStorage.quantity);
document.getElementById("firstname").value = sessionStorage.firstname;
document.getElementById("lastname").value = sessionStorage.lastname;
document.getElementById("street").value = sessionStorage.street;
document.getElementById("suburb").value = sessionStorage.suburb;
document.getElementById("state").value = sessionStorage.state;
document.getElementById("postcode").value = sessionStorage.postcode;
document.getElementById("phone").value = sessionStorage.phone;
document.getElementById("email").value = sessionStorage.email;
document.getElementById("preferred").value = sessionStorage.preferred;
document.getElementById("deal").value = sessionStorage.deal;
document.getElementById("quality").value = sessionStorage.quality;
document.getElementById("quantity").value = sessionStorage.quantity;
document.getElementById("extrabags").value = sessionStorage.extrabags;
document.getElementById("accomodation").value = sessionStorage.accomodation;
document.getElementById("travel").value = sessionStorage.travel;
document.getElementById("prohibiteditems").value = sessionStorage.prohibiteditems;
document.getElementById("disabilityprecaution").value = sessionStorage.disabilityprecaution;
}
}
function cancelBooking() {
window.location = "index.html";
}
function init() {
getInfo();
var payment = document.getElementById("payment");
payment.onsubmit = validate;
var cancel = document.getElementById("cancel");
cancel.onclick = cancelBooking;
}
window.onload = init;

It might be that the ID at var payment = document.getElementById("payment"); is wrong and JS can't find it, also if you are calling some function you should do it like this payment.onsubmit = validate(); check that the ID is correct.

make sure your <script> tag is in the last before the </body> tag. like below
<html>
<head>
</head>
<body>
<form>
</form>
<script type="text/javascript" src="script.js"></script>
</body>
</html>
but not like this
<html>
<head>
<script type="text/javascript" src="script.js"></script>
</head>
<body>
<form>
</form>
</body>
</html>

Encode letter to number

I feel like I am failing everything this semester. but I was wondering if you all could help me with a JS project. We have been tasked with essentially converting numbers to letters and vica versa using textareas in HTML. I was able to do the numbers to letters function, but am having difficulties going the other way. what I have for all is:
var $ = function(id) {
return document.getElementById(id);
};
window.onload = function() {
$("btnDecode").onclick = fnDecode;
$("btnEncode").onclick = fnEncode;
$("btnClear").onclick = fnClear;
};
function fnDecode() {
var msg = $("textin").value;
if (msg === "") {
$("textin_span").innerHTML = "* Please enter a message to decode *";
$("textin").focus;
return;
} else {
$("textin_span").innerHTML = "";
}
var nums = msg.split(",");
var outstr = "";
for(var i=0; i < nums.length; i++) {
var n2 = parseInt(nums[i]);
if (isNaN(n2)) {
outstr += "?";
} else if (isNallN(nums[i])) {
} else if (n2 === 0) {
outstr += " ";
} else if (n2 < 1 || n2 > 26) {
outstr += "?";
} else {
outstr += String.fromCharCode(n2+64);
}
$("textout").value = outstr;
}
}
function isNallN(s) {
//parse string to check all characters are digits
}
function fnEncode() {
var msg = $("textin").value.toUpperCase();
$("textin").value = msg;
if (msg === "") {
$("textin_span").innerHTML = "* Please enter numberse to decode *";
$("textin").focus;
return;
} else {
$("textin_span").innerHTML = "";
}
var c;
var outstr = "";
for (var i=0; i<msg.length; i++);
c = msg.charCodeAt(i);
if (typeof c === "number") {
outstr += "99";
}else if (c === " ") {
outstr += 0;
/*} else if (c[i] >= "A" && c[i] <= "Z") {
outstr += "99";*/
} else {
outstr += String.charCodeAt(c - 64);
}
$("textout").value = outstr;
//var x = msg.charAT(i);
}
obviously isNallN is not complete, but he promised us if we could figure out fnEncode we should be able to do isNallN with no issues (which I am hoping is true lol) What am doing wrong though in fnEncode? Every time I run it, it gives me "99" even when I put letters in.

Translating jQuery to javascript [closed]

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I'm new to SO and to JS. I want to translate this code to pure JS but I'm really struggling. May someone help me please?
$(document).ready(function(){
var displayFix = function(num) {
if (num.length > 9) {
total.text(num.substr(0,9));
}
};
var number = "";
var newNumber = "";
var operator = "";
var total = $(".display");
total.text("0");
$(".numbers span").not(".clear, .dot").click(function(){
number += $(this).text();
total.text(number);
displayFix(number);
});
$(".dot").click(function() {
if ( number.length == 0)
{ number = "0.";
} else {
number += $(this).text();
total.text(number);
displayFix(number);
};
});
$(".operators span").not(".igual").click(function(){
operator = $(this).text();
newNumber = number;
number = "";
total.text("0");
});
$(".clear").click(function(){
number = "";
total.text("0");
newNumber = "";
});
$(".igual").click(function(){
if (operator === "+"){
number = (parseFloat(newNumber,10) + parseFloat(number,10)).toString(10);
} else if (operator === "-"){
number = (parseFloat(newNumber,10) - parseFloat(number,10)).toString(10);
} else if (operator === "/"){
number = (parseFloat(newNumber,10) / parseFloat(number,10)).toString(10);
} else if (operator === "*"){
number = (parseFloat(newNumber,10) * parseFloat(number,10)).toString(10);
}
total.text(number);
displayFix(number);
number = "";
newNumber = "";
});
$(document).keypress(function(event){
var keycode = (event.keyCode ? event.keyCode : event.which);
if (keycode === 49) {
$("#num1").click();
} else if (keycode === 50) {
$("#num2").click();
} else if (keycode === 51) {
$("#num3").click();
}
});
});
I suppose I can replace the following lines:
var total = $(".display") with var total = document.querySelector(".display")
total.text("0") with total.innerHTML="0"
$(".dot").click(function() { with document.querySelector(".dot").onclick = function() {
Also, the browser I'm using is a updated Chrome and I don't need it to support other browsers.

youmightnotneedjquery is your friend.
You'll see that you can define your own replacement for jQuery.ready():
function ready(fn) {
if (document.readyState != 'loading'){
fn();
} else {
document.addEventListener('DOMContentLoaded', fn);
}
}
Then you'll need to get used to do without jQuery wrapper, which means dealing with array indexes and possibly empty results. So for instance document.querySelector(".dot").onclick = function() { is not going to be enough, you want to do
var dots = document.querySelector(".dot");
for(var i=0; i<dots.length; i++ ){
dots[i].onclick = function() { ... }
}
Finally, you need to discard elements manually since you have no jQuery .not():
var operators = document.querySelector(".operators span");
for(var i=0; i<operators.length; i++ ){
var operator = operators[i];
if(operator.className.indexOf("igual") < 0){
//do stuff
}else{
//don't
}
}
Note: you may want to use document.getElementById() and document.getElementsByClassName when your selector is just an id or a class.
Hope this short guidance is enough for you to start.

The Javascript equivalent will almost look like this for your jquery code,
(function() {
var displayFix = function(num) {
if (num.length > 9) {
total.innerHTML = num.substr(0, 9);
}
};
var number = "";
var newNumber = "";
var operator = "";
var total = document.getElementsByClassName("display");
total.innerHTML = "0";
var sel1 = document.querySelector(".numbers span");
for (var i = sel1.length; i--;) {
if (sel1[i].className != 'clear' && sel1[i].className != 'dot') {
var arg = sel1[i].innerHTML;
sel1[i].onclick = function(arg) {
return function() {
number += arg;
total.innerHTML = number;
displayFix(number);
};
};
}
}
var sel2 = document.querySelector(".dot");
sel2.onclick = function() {
if (number.length == 0) {
number = "0.";
} else {
number += sel2.innerHTML;
total.innerHTML = number;
displayFix(number);
};
};
var sel3 = document.querySelector(".operators span");
for (var i = sel3.length; i--;) {
if (sel3[i].className != 'igual') {
var arg = sel3[i].innerHTML;
sel3[i].onclick = function(arg) {
return function() {
operator = arg;
newNumber = number;
number = "";
total.innerHTML = "0";
};
};
}
}
document.querySelector(".clear").onclick = function() {
number = "";
total.innerHTML = "0";
newNumber = "";
};
document.querySelector(".igual").onclick = function() {
if (operator === "+") {
number = (parseFloat(newNumber, 10) + parseFloat(number, 10)).toString(10);
} else if (operator === "-") {
number = (parseFloat(newNumber, 10) - parseFloat(number, 10)).toString(10);
} else if (operator === "/") {
number = (parseFloat(newNumber, 10) / parseFloat(number, 10)).toString(10);
} else if (operator === "*") {
number = (parseFloat(newNumber, 10) * parseFloat(number, 10)).toString(10);
}
total.innerHTML = number;
displayFix(number);
number = "";
newNumber = "";
};
document.querySelector(".igual").onkeypress = function(event) {
var keycode = (event.keyCode ? event.keyCode : event.which);
var elm = "";
if (keycode === 49) {
elm = document.getElementById("num1");
elm.onclick.apply(elm);
} else if (keycode === 50) {
elm = document.getElementById("num2");
elm.onclick.apply(elm);
} else if (keycode === 51) {
elm = document.getElementById("num3");
elm.onclick.apply(elm);
}
};
})();
Disclaimer: The code is just converted to the JavaScript equivalent, not tested with any values.

four repeating letters check javascript, spam detection

Is there a a "smarter" way to do this? This works but I imagine has something to do with for loops, what if I was checking for 20 repeating characters?
What happens if javascript is disabled?
Is there an easier way to check for "sensical" posts instead of say aldjfalkfja;lfjaklfjlkfj how would I filter that out without storing a library of words and comparing the string to those?
function counter(){
this.value = 0;
}
var count = new counter();
function updatecount(fnc){
fnc.value = count.value + 1;
}
function charbank1(){
this.value = "";
}
var cb1 = new charbank1();
function insertchar1(fnc){
fnc.value = cb1.value + String.fromCharCode(keynum);
}
function charbank2(){
this.value = "";
}
var cb2 = new charbank2();
function insertchar2(fnc){
fnc.value = cb2.value + String.fromCharCode(keynum);
}
function charbank3(){
this.value = "";
}
var cb3 = new charbank3();
function insertchar3(fnc){
fnc.value = cb3.value + String.fromCharCode(keynum);
}
function charbank4(){
this.value = "";
}
var cb4 = new charbank4();
function insertchar1(fnc){
fnc.value = cb4.value + String.fromCharCode(keynum);
}
function repeatingcharcheck(){
if(count.value < 4){
if(count.value == 1){
insertchar1(cb1);
}
if(count.value == 2){
insertchar2(cb2);
}
if(count.value == 3){
insertchar3(cb3);
}
if(count.value == 4){
insertchar4(cb4);
}
}else{
if(cb1.value == cb2.value == cb3.value == cb4.value){
alert('four letters in a row is not allowed');
window.location.replace('somewhere.com');
}
}
}

Javascript code broken

This is my first attempt at a little more complex code structure. The thing is my IDE says it technically works , jsfiddle says it doesn't, it actually initializes only the two confirm functions that I declared "confirmUserName();" and "confirmFullName();"
Can someone explain why i did such a horrible job.
var userList = [];
var username = "";
var fullname = "";
var addUserName = addUser(username, userList); v
var addFullName = addUser(fullname, userList);
function addUser(usrName, list) {
if(list.length == 0) {
list.push(usrName); // userlist empty add the new user
} else {
for (var i = 0; i < list.length; i++) {
if(list[i] == undefined) {
list[i] = usrName;
return list;
} else if(i == list.length - 1) {
list.push(usrName);
return list;
}
}
}
} // Function that adds user and name to list
var usernameQuery;
function confirmUserName() {
confirm("Is " + username + " your first choice?");
if (confirmUserName == true) {
return fullnameQuery;
} else {
return usernameQuery;
}
}
var fullnameQuery; /
function fullnameConfirm() {
confirm("Is " + fullname + " your first choice ");
if (fullnameConfirm == true) {
return startRide;
} else {
return fullnameQuery;
}
}
if(username == undefined) {
usernameQuery = function() {
username = prompt("You are the first user to play, \n" +
" Chose and let the game begin !");
return addUserName;
};
} else {
usernameQuery = function() {
username = prompt("What username whould you like to have ? \n" +
" Chose and let the game begin !");
return addUserName;
};
}
confirmUserName();
if(fullname == undefined) {
fullnameQuery = function() {
fullname = prompt("Enter your real name !");
return addFullName;
};
} else {
fullnameQuery = function() {
fullname = prompt("Enter your real name!");
return addFullName;
};
}
fullnameConfirm();

There is a lot wrong with the code you posted -- I'll just take one chunk:
function confirmUserName() {
// The return value of `confirm` is ignored.
confirm("Is " + username + " your first choice?");
// confirmUserName is the name of your function.
// You sould be using `===` instead of `==`
// Or, not comparing against true at all.
if (confirmUserName == true) {
return fullnameQuery;
} else {
return usernameQuery;
}
}
Fixed function:
function confirmUserName() {
var res = confirm("Is " + username + " your first choice?");
if (res) {
return fullnameQuery;
} else {
return usernameQuery;
}
}

It does not throw Errors with this, but I dont know in which situation you want your code to be implemented and what it should do, I hope this is what you need:
var userList = [];
var username = "";
var fullname = "";
var addUserName = addUser(username, userList);
var addFullName = addUser(fullname, userList);
function addUser(usrName, list) {
if (list.length === 0) {
list.push(usrName); // userlist empty add the new user
} else {
for (var i = 0; i < list.length; i++) {
if (list[i] === undefined) {
list[i] = usrName;
return list;
} else if (i == list.length - 1) {
list.push(usrName);
return list;
}
}
}
} // Function that adds user and name to list
var usernameQuery;
function confirmUserName() {
confirm("Is " + username + " your first choice?");
if (confirmUserName === true) {
return fullnameQuery;
} else {
return usernameQuery;
}
}
var fullnameQuery;
function fullnameConfirm() {
confirm("Is " + fullname + " your first choice ");
if (fullnameConfirm === true) {
return startRide;
} else {
return fullnameQuery;
}
}
if (username === undefined) {
usernameQuery = function () {
username = prompt("You are the first user to play, \n" +
" Chose and let the game begin !");
return addUserName;
};
} else {
usernameQuery = function () {
username = prompt("What username whould you like to have ? \n" +
" Chose and let the game begin !");
return addUserName;
};
}
confirmUserName();
if (fullname === undefined) {
fullnameQuery = function () {
fullname = prompt("Enter your real name !");
return addFullName;
};
} else {
fullnameQuery = function () {
fullname = prompt("Enter your real name!");
return addFullName;
};
}
fullnameConfirm();