JS onmousedown limited to left-click - onmousedown

Question

I have built a sort of picture gallery in JS. On given img and p elements, the onmousedown events calls two functions: it loads a new image and a new description (see below)
But, as opposed to what I was thinking, the onmousedow it is triggered by right-click too. I don't like this and I'd love to limite the onmousedown event to the left-click of the mouse.
Is there any way to do this?
Many thanks for your help.
HTML:
<img style="max-width: 100%; cursor:pointer;" src="../../img/picture1.jpg" alt="text" title="click me"
id="showgallery" onmousedown="changeimg(); changedscrpt()" />
enter code here
<p class="myclass" style="text-align: center;" id="imgdescription">Description</p>

Answer 1

You should move out calls to changeimg() and changedscrpt() to separate method which would evaluate first whether left mouse was pressed, something like that:
onmousedown="checkAndChange(event, this)";
JavaScript:
function checkAndChange(e, obj)
{
if (leftMousePressed(e))
{
changeimg();
changedscrpt();
}
}
function leftMousePressed(e)
{
e = e || window.event;
var button = e.which || e.button;
return button == 1;
}
If the right mouse button will be pressed, JavaScript will not do anything (will not change next image).