I would to make the iFrame to appear on fullscreen with a button click using JavaScript.
You will have to do two things: make the window fullscreen, and then the <iframe>
to fill up the whole size.
You can make it go fullscreen with JS such as in this SO answer.
Then, to make it full size, just add a few styles, like below. What this JS script does is add a class with those styles to the <iframe>
.
JS
document.getElementsByTagName("iframe")[0].className = "fullScreen";
CSS
body, html {
height: 100%;
margin: 0;
}
.fullScreen {
width: 100%;
height: 100%;
position: absolute;
top: 0;
left: 0;
}
See this partially working* example on JSFiddle.
*partially working because JSFiddle doesn't allow the fullscreen method because it deems it unsafe. But it should work for you.