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JavaScript unexpected undefined value [closed]

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Closed 29 days ago.
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I am running the following JavaScript code:
// Return true if the given username and password are in the database,
// false otherwise.
function validCredentials(enteredUsername, enteredPassword) {
// Database of usernames and passwords
let usernames = ["smith", "tron", "ace", "ladyj", "anon"];
let passwords = ["qwerty", "EndOfLine", "year1942", "ladyj123", "PASSWORD"];
// Search the usernames array for enteredUsername
// Only return true if the enteredUsername is in username, and the
// same location in passwords is enteredPassword
if (usernames.includes(enteredUsername)){
var correctPassword = passwords[usernames.indexOf(enteredUsername)];
if(enteredPassword == correctPassword){
return true;
}
}
else {
return false;
}
}
console.log("Login for ladyj: " + validCredentials("ladyj", "ladyj123")); // true
console.log("Login for ace: " + validCredentials("ace", "wrong")); // false
console.log("Login for jake: " + validCredentials("jake", "???")); // false
I am expecting console.log("Login for ace: " + validCredentials("ace", "wrong")); return false, but it returned undefined. Can anyone tell me what went wrong?

You don't return in all possible branches (namely, if the username exists, but the password is incorrect). Move the return false outside the else to be the final statement in the function.
Alternatively, you could simplify the chain of if and else into one statement:
return usernames.includes(enteredUsername) &&
passwords[usernames.indexOf(enteredUsername)] === enteredPassword;

Second Line of Else Block Not Running [closed]

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Closed 12 months ago.
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In my else block, the second line does not appear to be running. It runs setHelperText but seems to ignore setAlertValue.
const [alertValue, setAlertValue] = useState("error");
const [errValue, setErrorValue] = useState("Error State");
const [helperText, setHelperText] = useState('Input "success" to remove error');
const handleChange = (e) => {
setErrorValue(e.target.value);
if (e.target.value === "success") {
setAlertValue(null);
setHelperText("Update input to re-enable error");
} else
setHelperText('Input "success" to remove error');
setAlertValue("error"); // this line does not run
};
<TextField
label="Error State"
message="this is an ERROR message"
alert={alertValue}
value={errValue}
onChange={handleChange}
helperText={helperText}
/>

Curly braces are missing in your code. It should be like this:
if (e.target.value === "success") {
setAlertValue(null);
setHelperText("Update input to re-enable error");
} else {
setHelperText('Input "success" to remove error');
setAlertValue("error");
};

Why are my variables not being correctly defined in my if...else statement? [closed]

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Closed 3 years ago.
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In the code below, I've defined a function called checkPassword(), which takes in a single argument, passwordCorrect, which will be either true or false.
I've also defined two variables, accessGranted and message, which currently have no values (they're undefined) and will be overwritten and defined by your if statement if you've written it correctly.
I need to write an if statement inside the function that updates the two variables, accessGranted (a boolean), and message (a string), to meet the requirements below
Requirements:
1) If passwordCorrect is true, accessGranted should have a value of true and message should have a value of 'Welcome to the admin panel!'
2) In any other case, accessGranted should have a value of false and message should have a value of 'Wrong password.'
var accessGranted;
var message;
function checkPassword(passwordCorrect) {
if passwordCorrect == true {
accessGranted = true;
message = "Welcome to the admin panel!";
}
else {
accessGranted = false;
message = "Wrong password."
}
}
console.log('Access Granted:', accessGranted);
console.log('Message:', message);

You need to call the function and fix your syntax error. If statements need parentheses in javascript.
let accessGranted;
let message;
function checkPassword(passwordCorrect) {
if (passwordCorrect) {
accessGranted = true;
message = "Welcome to the admin panel!";
}
else {
accessGranted = false;
message = "Wrong password."
}
}
checkPassword(true)
console.log('Access Granted:', accessGranted);
console.log('Message:', message);

`await` command causes variable to lose scope [closed]

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Closed 4 years ago.
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I am using await to pull data from the database. There's a variable secuity_ok that is true on one line, and then false on the next. Can anyone see what the issue is?
Note – if I comment out the line: let session = ..., then it all works.
Controller.prototype.changePassword = async function(request, response) {
let model = request.body;
var secuity_ok = false;
var user = await userService.getUserByEmail(model.email);
if (user && this.isAuthenticatedUser(request, user.id)) {
secuity_ok = true;
} else {
let session = await authenticationService.createSessionByEmailPassword(model.email, model.oldpassword),
secuity_ok = !!session;
console.log( 'A', secuity_ok ); // true
}
console.log( 'B', secuity_ok ); // false
if (!secuity_ok) {
this.sendForbiddenError(response, {
error: 'Cannot change password: Application safeguards are preventing this action'
});
return new Promise(() => {});
}
...
}
Output:
A true
B false
Output should be:
A true
B true

You have a comma at the end of the first line here:
let session = await authenticationService.createSessionByEmailPassword(model.email, model.oldpassword), // <--- Note comma here
secuity_ok = !!session;
That makes secuity_ok part of the let statement, so it's an extra, inner declaration of secuity_ok that only has scope inside the parentheses of the else clause.

Javascript "Refference error" [closed]

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Closed 8 years ago.
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I have this file upload.js which contains this:
var app = app | {};
(function(o){
"use strict";
//Private methods
var ajax, getFormData, setProgress;
ajax = function(data){
var xmlhttp = new XMLHttpRequest(), uploaded;
xmlhttp.open('post', o.options.processor);
xmlhttp.send(data);
};
getFormData = function(source){
};
setProgress = function(value){
};
o.uploader = function(options){
o.options = options;
if(o.options.files !== undefined){
ajax({});
}
}
})(app);
and I have this in my upload.php:
<script type="javascript/text" src="<? echo APP_ROOT; ?>public/js/upload.js"></script>
<script>
var pathname = window.location.protocol + "//" + window.location.host + "/";
document.getElementById('submit').addEventListener('click', function(e){
e.preventDefault();
var f = document.getElementById('file'),
pb = document.getElementById('pb'),
pt = document.getElementById('pt');
app.uploader({
files: f,
progressBar: pb,
progressText: pt,
processor: pathname,
finished: function(data){
console.log(data);
},
error: function(){
console.log('Not working!');
}
});
});
</script>
and every time I click on the submit button I get this javascript error in my console ReferenceError: app is not defined what is wrong with it ? Please help.

Change the Pipe sign to logical OR operator sign instead of using a Bitwise OR operator. (as per suggestion/correction by pid)
var app = app || {};
It would fix it.

In javascript, the || works like coalesce.
If the first term (term before ||) is falsy, the assignment is given to the second term (term after ||).
The | is bitwise or in js.
|| is also short circuit or operator as it is in many other languages.