CODEWITHSUNDEEP
javascriptfunctionvariablesbooleanreturn
Sawyer
Sawyer

Reputation: 77

Difficulty returning a variable via a function

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?

Upvotes: 0

Views: 118

Answers (3)

001
001

Reputation: 13533

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);

Upvotes: 1

James South
James South

Reputation: 10645

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);

Upvotes: 0

DJafari
DJafari

Reputation: 13545

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 .

Upvotes: 0

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