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Pass window variable as parameter in Javascript [duplicate]

This question already has answers here:
Is JavaScript a pass-by-reference or pass-by-value language?
(33 answers)
Closed 2 years ago.
Passing a window global variable through JS does not seem to be working. The following code is printing true:
window.nada = true;
tata(window.nada);
console.log(window.nada);
function tata(lala) {
lala = false;
}
How can I affect the window.nada global variable inside the tata function?

Technically, JavaScript uses call-by-sharing.
In practice, you'll have to pass the entire window object, as well as the name of the property you want to change:
tata(window, 'nada');
function tata(window, prop)
{
window[prop] = false;
}

Your window.nada is a primitive data type (Boolean).
Primitive data types are passed to the function per value and not per reference. So inside your tata function the lala variable does not know anything about the window.nada value

JavaScript function not working when passing variable instead of hard coded value [duplicate]

This question already has answers here:
Using a string to access a variable
(3 answers)
Closed 3 years ago.
I have a JS function as below
// A simple array where we keep track of things that are filed.
filed = [];
function fileIt(thing) {
// Dynamically call the file method of whatever 'thing' was passed in.
thing.file();
// Mark as filed
filed.push(thing);
}
Now, function fileIt(thing) is working well when called as below
fileIt(AuditForm);
Whereas, its giving error at line thing.file(); when i am trying to pass a variable like below
var formID = obj.id;
fileIt(formID);
Variable formID has same value and i.e. "AuditForm" what's wrong here. Kindly suggest.

If obj.id is the string AuditForm, then you have no choice but to use dynamic property notation on the global window object, or use eval if you didn't declare AuditForm with var on the global scope:
If you declare AuditForm with var on the global scope:
fileIt(window[formID]);
If you don't:
fileIt(eval(formID));
Do note that eval is a very poor option, as if obj.id can be interpreted as other code, e.g. another eval call which will be evaluated, then malicious operations can be performed. Example:
const obj = {
id: "eval('alert(\"Inside an eval script!\")')"
};
eval(obj.id);

Assigning the value of a javascript variable within function arguments? [duplicate]

This question already has answers here:
Javascript - String concatenation [duplicate]
(2 answers)
Closed 6 years ago.
I'm sending an XMLHttpRequest.
In the open function I want to set some parameters for the request.
req.open('GET', /some/path?someparam=*somevariable*, true)
I want to get someparam to equal the value of a variable, like var somevariable. In fact the variable name might even have the same name as someparam.
How do I get the variable to resolve in this instance?

String concatenation and encodeURIComponent to make sure you are producing a valid URI:
'/some/path?someparam=' + encodeURIComponent(somevariable)
In an ES6 environment you can use template literals:
`/some/path?someparam=${encodeURIComponent(somevariable)}`

Do Javascript variable assignments work by reference? [duplicate]

This question already has answers here:
JavaScript by reference vs. by value [duplicate]
(4 answers)
Closed 8 years ago.
I have a question about referencing objects in javascript.
Say I have a variable that is some object (lets say json) and it is called objOne - (var objOne = someJSONObject;).
If I go ahead and declare
var objTwo = objOne;
will I have two references to the same Object? Kind of like a c pointer?

To sum it up :
assignements are done by value
you never manipulate objects, only object references
This means that
you'll have two references to the same object (you can check that by changing a property of the object)
when you're passed in a variable the value of a primitive, changing your variable doesn't change other variables
EDIT : as it's a duplicate I'll delete this answer in a minute to allow a proper closing if there's no other answer. Please vote to close.

Yes, objects are passed by reference:
function changeVal(obj){
obj.value = "bar"
}
(function checkRefs(){
var myObject = {
value: "foo"
};
alert(myObject.value);
changeVal(myObject);
alert(myObject.value);
})();

Updating object values in JavaScript via function [duplicate]

This question already has answers here:
Add a property to a JavaScript object using a variable as the name? [duplicate]
(14 answers)
Closed 9 years ago.
In JavaScript I am trying to update an object value through a function, through which I am passing the object property to update.
However, this won't work - and I can see why, but don't know how to combat it!
myObject = {"testItem": "testValue"};
console.log(myObject.testItem);
function updateSomeValue(objectItem, newValue){
myObject.objectItem = newValue;
}
updateSomeValue('testItem', 'newValue');
console.log(myObject.testItem);
Now, I can see the issue here is that in the function, myObject.objectItem is expecting an item in the object called objectItem - it won't translate it to testItem.
How do I do this?

By using a different notation. Using [ .. ] you can specify the property name as a string.
function updateSomeValue(objectItem, newValue){
myObject[objectItem] = newValue;
}