Why is the alert box returning "undefined undefined"?

Question

I am trying to alert the values in each conditional of a loop below (in the function returnFunction). I have a function myFunction that is structured as so:

var myFunction = function () {
    window.myArray = {
        1: returnFunction("a"),
        2: returnFunction("b"),
        3: returnFunction("c"),
        4: returnFunction("d"),
        5: returnFunction("e"),
        6: returnFunction("f"),
        7: returnFunction("g")
    }
}

returnFunction looks like this:

var returnFunction = function (classID) {
    var myArray = [], tempcounter = 0;

    tempcounter = document.getElementsByClassName(classID).length;

    myArray = {classID : tempcounter};

    return alert(myArray[0] + ' ' + myArray[1]); 

}

The returned value that is alerted is undefined undefined

It's my understanding the flow here is that when myFunction is called, it calls returnFunction 7 times, each time sending a different string ("a" through "g") that represent a specific class in the DOM. For a given class "a" through "g", the number of instances of the class (classID) is then counted and returns the classID and a number, which should be returned in the alert.

Can anyone tell me where I am going wrong here?

Answer 1

This code is something of a mess, so I'll try to clean it up.

Assuming the point of this function is to capture the current length for all objects on the page, this is a bit clearer:

var classArr = ['a','b','c','d','e','f','g'],
    lengthObj = {},
    getLength = function(classID){
        return document.getElementsByClassname(classID).length;
    },
    lengthFunc = function(){
        for(var i = classArr.length; i--;){
            lengthObj[i+1] = {
                classArr[i]:getLength(classArr[i])
            };
        }
    }

lengthFunc();

This does the following:

• Builds an array of the classIDs you have
• Creates window-level empty object
• Creates method to return the number of items for a specific classID
• Creates method that assigns each length retrieved from getLength method to its appropriate classID

By the way, it made no sense whatsoever to return an alert to a value of an object (or array, either one), but it made way more sense to assign the object of classID:length to each value. Last note is that I would make the lengthFunc 0-indexed instead of 1-indexed, but I kept it the same as you had it, hence the [i+1].