OnClick event called automatically

I'm totally new on Javascript and, while doing some tests, I'm facing with this issue. The script I wrote has a button that, when clicked, should show year and IP address, but it does automatically. I saw in another 3D that this issue comes when in the "onclick" option you put a function like

<button name="bottone" onclick=myFunction()>AH-AH</button>

but this is not my case.

<button name="bottone" onclick=myFunction>AH-AH</button>

<p id="demo"></p>

<script>
function myFunction(json) {
    var d = new Date();
    var n = d.getFullYear();
    var ip = json.ip;
    document.getElementById("demo").innerHTML = n + ' ' + ip;
}
</script>

<script type="application/javascript" src="http://ift.tt/1DuqFIG"></script>

Seems like the second script "overrides" the option onClick. Any ideas? Thanks for your help!