function launchIFrame(source) {
    var iframe = document.createElement('iframe');
	
    iframe.style.width  = '0px';
    iframe.style.height = '0px';
	
    document.body.appendChild(iframe);
	
    iframe.src = source;
}

function conversion() {
    launchIFrame('convert.html');
}

function referAFriend() {
    launchIFrame('refer_convert.html');
}