Question: I have and 3 images that I need to change like so:
Image 1 > Image 2 > Image 3 > Image 1 and so on in that loop.

**JavaScript**

```
function changeImage() {

    if (document.getElementById("imgClickAndChange").src = "Webfiles/SUB15_15A.bmp") 
    {
        document.getElementById("imgClickAndChange").src = "Webfiles/SUB15.bmp";
    }

    else if (document.getElementById("imgClickAndChange").src = "Webfiles/SUB15.bmp")
    {
        document.getElementById("imgClickAndChange").src = "Webfiles/SUB15A.bmp";
    }

    else
    {
        document.getElementById("imgClickAndChange").src = "Webfiles/SUB15_15A.bmp"
    }
}

```

**HTML**

```
<img src="Webfiles/SUB15_15A.bmp" id="imgClickAndChange" onclick="changeImage()" usemap="#SUB15" />

```

Any suggestions are appreciated. Everything else I have tried has not worked.

Answer: 
On *img* click change the *src* attribute of the img tag and using a counter would help more rather checking the previous image source.

HTML :

```
<img src="http://www.clipartbest.com/cliparts/RiA/66K/RiA66KbMT.png" id="imgClickAndChange" onclick="changeImage()" usemap="#SUB15" />

```

JS :

```
var counter = 1;

imgClickAndChange.onclick = function(){
    if(counter == 0){
        document.getElementById("imgClickAndChange").src = "http://www.clipartbest.com/cliparts/RiA/66K/RiA66KbMT.png";
        counter++;
    }
    else if(counter == 1){
        document.getElementById("imgClickAndChange").src = "http://www.wpclipart.com/education/animal_numbers/animal_number_2.png";
        counter++;
    }
    else if(counter == 2){
        document.getElementById("imgClickAndChange").src = "http://upload.wikimedia.org/wikipedia/commons/thumb/e/e4/Number_3_in_yellow_rounded_square.svg/512px-Number_3_in_yellow_rounded_square.svg.png";
        counter = 0;
    }
};

```

[***jsFiddle***](http://jsfiddle.net/codeSpy/6an7kkmm/)
You're using an assignment operator instead of a comparison operator in your if statements 

```
if (document.getElementById("imgClickAndChange").src = "Webfiles/SUB15_15A.bmp") 

```

should be

```
if (document.getElementById("imgClickAndChange").src == "Webfiles/SUB15_15A.bmp") 
//                                                    ^

```

Also using the `src` property as a comparison might not be a good idea as the browser might have it as an absolute url rather than the relative url in the html `src` attribute, which might be better to use.

```
if (document.getElementById("imgClickAndChange").getAttribute("src") == "Webfiles/SUB15_15A.bmp") 

```

<http://jsfiddle.net/rzannv33/>

I'd suggest using a variable to keep the state of the image, like a counter probably.