I know it's a very old thread, but I would like to add my findings here for future reference.
I found the following code wasn't working:
function swapImage() {
var element = document.getElementById("myImage");
if (element.src == "image1.png") {
element.src = "image2.png";
} else {
element.src = "image1.png"
}
}
Showing alerts containing the element.src taught me it contained the full path to the image in my local machine. Thus, the if statement had been always evaluated to false.
To fix that in a logical manner, what I did was get the attribute of the element, as the following code shows.
function swapImage() {
var element = document.getElementById("myImage");
if (element.getAttribute("src") == "image1.png") {
element.src = "image2.png";
} else {
element.src = "image1.png";
}
}
By using the function getAttribute("attributeName"), I was able to retrieve the path contained in the src relatively to the project directory.
like.src == 'vote_triangle.png'. Note the==. Otherwise, you're assigninglike.srcin theif.