Difficulty returning a variable via a function

Question

I'm trying to return variables as true or false via a function. I want to do it this way so I can call ajax only once, and receive both variables back in one function. However, I'm having trouble returning the variable. Here is my code:

var emailExists = false;
var userExists = false;

function checkExisting(emailExists,userExists) {
    var emailExists = true;
return emailExists;
}
alert(emailExists);

What I can't figure out is why the alert gives me false, when I thought it'd be giving me true. What's wrong with this setup?

001 · Accepted Answer · 2011-05-07 17:28:37Z

1

You have 3 versions of the "emailExists" variable: the global one, the parameter to checkExisting(), and the local one in checkExisting()! Get rid of all but the first one. Also, you never call checkExisting().

var emailExists = false;

function checkExisting() {
    emailExists = true;
}
checkExisting();
alert(emailExists);

or

var emailExists = false;

function checkExisting() {
    return true;
}
emailExists = checkExisting();
alert(emailExists);

answered May 7, 2011 at 17:28

001

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1 Comment

Sawyer Over a year ago

Awesome! This is exactly what I needed. Thank you very much, I'll be using this.

DJafari · Accepted Answer · 2011-05-07 17:00:43Z

0

var emailExists = false;
var userExists = false;

function checkExisting(emailExists,userExists) {
    emailExists = true;
return emailExists;
}
checkExisting(false,true); //FOR EXAMPLE !
alert(emailExists);

You should call checkExisting function, and not needed use from var into body of function, because it's defined on page .

answered May 7, 2011 at 17:00

DJafari

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1 Comment

Sawyer Over a year ago

Thanks for the response! This works fine, however I'd like to use an ajax check inside the function to tell whether these functions are true or not. Using that system when calling the function doesn't check for that. Thats's why I had it become true in the function, but that's the issue. Any idea how to do it that way?

James South · Accepted Answer · 2011-05-07 17:13:30Z

0

In short... everything.

I take it you are new to javascript and programming? You need to do a lot of reading so that you understand object scope and how javascript works. I'll give you a quick run-through of what you have written so you can hopefully learn something.

// Here you're declared two objects. 'emailExists' and 'userExists'.
// These Boolean objects, since they are not wrapped in a closure are now global
// (you can reference them anywhere) in your script.   
var emailExists = false;
var userExists = false;


// This function never gets called. If it did, it would always return true 
// since you have created a new 'emailExists' Boolean object in your function 
// and would return that each time.
function checkExisting(emailExists,userExists) {
    // This whilst only available within the function closure, is a no, no.
    // You're just confusing things by creating objects with the same name 
    // as global ones.
    var emailExists = true;

    // I'm returning true.
    return emailExists;
}

// Here you are returning your first declared Boolean (the one at the top)
// this will always return false.
alert(emailExists);

answered May 7, 2011 at 17:13

James South

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1 Comment

Sawyer Over a year ago

Alright, I see. I actually have the function called just before that, I didn't include it, though. But thank you very much, I appreciate it!

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