I have a variable that I pass into a function, and return its updated value. The syntax looks very similar to:
var myName = 'hello all.'; FuncUpperCase(myName); function FuncUpperCase(myName) { myName = myName.toUpperCase(); return myName; } But the variable myName doesn't seem to be modified with the value from toUpperCase().
Note: I don't want to write var newName = FuncUpperCase(myName), because I don't like that syntax.
This might answer your question:
Pass a string by reference in Javascript
Alternatively, pass an object and not a string.
var something = {}; something.word = "word"; var allcaps = function(inp) {inp.word = inp.word.toUpperCase();}; allcaps(something); //something.word has now been changed alert(something.word); 
In JavaScript, everything is passed by value. It means that if you reassign a value for a given parameter in a function, you will not modify the value outside of the scope of the given function. Another important thing to understand, is how value to object references work: if you pass an object to a function, it is also by value that it is given, but if you access a property of this object, then the actual object will be modified outside of the function too, but NOT the value (that is to say, the value which is a reference to the object).
In the end you have to pass an object to your function and modify a property of it to make it persist outside.
function setToUpperCase(object, key) { object[key] = ('' + object[key]).toUpperCase(); return object[key]; } And use it like this:
var holder = { word: 'blah' }; setToUpperCase(holder, 'word'); console.log(holder.word); // BLAH 
everything is passed by value : false, in your example holder is passed by reference...
object = {}; it will not change the value of object, ever, it will change the value that was the reference to object.