Javascript accessing object and array defined in modular function - scope

Question

This is a bit foreign to me and I'm probably not understanding it correctly. This is what I have:
var imgModule = (function() {
var imgLocations = {};
var images = [];
imgLocations.setImage = function(img, location) {
imgLocations[img] = location;
}
imgLocations.getImg = function(img) {
return imgLocations[img];
}
imgLocations.setImageArray = function(img) {
images.push(img);
}
imgLocations.getImageArray = function() {
return images;
}
return imgLocations;
}());
I want to be able to access the imgLocations Object and images array from outside this function. The setting functions work, but
document.getElementById("but").onclick = function() {
console.log(imgModule.imgLocations.getImageArray());
console.log(imgModule.imgLocations.getImg(imgName));
}
Both return "undefined". How do I access these variables? And how can I improve this function? Please be patient with me and explain what I'm doing wrong :) I'm trying to learn it the right way instead of defining a global variable outside all functions.

Answer 1

The reason why this isn't working, is because your imgModule is returning the imgLocations object. That being the case, imgModule will actually be the imgLocations object. So you would access your methods like so:
imgModule.setImage()
imgModule.getImg()
imgModule.getImageArray()
imgModule.setImageArray()
And as #gillesc stated. If you are wanting to keep the current syntax of imgModule.imgLocations.getImg() then you could return the imgLocations like so
return {
imgLocations: imgLocations
}
doing so would allow you to add more functionality to your module
return {
imgLocations: imgLocations,
otherObject: otherObject
}
...
imgModule.otherObject.someFunctionCall();

Answer 2

The problem is you are returning the object created and are not setting it as a property of an object.
So in your case this is how it would work.
document.getElementById("but").onclick = function() {
console.log(imgModule.getImageArray());
console.log(imgModule.getImg(imgName));
}
What you need to do is return it like this
return {
imgLocations: imgLocations
}
If you want the API you are attending to create and still have access to the array which you can not do currently.

Answer 3

You don't access imgModule.imgLocations, since what you return is imgLocations, you should access them as:
document.getElementById("but").onclick = function() {
console.log(imgModule.getImageArray());
console.log(imgModule.getImg(imgName));
}

Answer 4

It seems you try to write module pattern.
For deep understanding, I recommend you following article:
The Module Pattern, by Addy Osmani
and pay attention to example with counter:
var testModule = (function () {
var counter = 0;
return {
incrementCounter: function () {
return counter++;
},
resetCounter: function () {
console.log( "counter value prior to reset: " + counter );
counter = 0;
}
};
})();
// Usage:
// Increment our counter
testModule.incrementCounter();
// Check the counter value and reset
// Outputs: counter value prior to reset: 1
testModule.resetCounter();