How to open a web page automatically in full screen mode

For Chrome via Chrome Fullscreen API

Note that for (Chrome) security reasons it cannot be called or executed automatically, there must be an interaction from the user first. (Such as button click, keydown/keypress etc.)

addEventListener("click", function() {
    var
          el = document.documentElement
        , rfs =
               el.requestFullScreen
            || el.webkitRequestFullScreen
            || el.mozRequestFullScreen
    ;
    rfs.call(el);
});

Javascript Fullscreen API as demo'd by David Walsh that seems to be a cross browser solution

// Find the right method, call on correct element
function launchFullScreen(element) {
  if(element.requestFullScreen) {
    element.requestFullScreen();
  } else if(element.mozRequestFullScreen) {
    element.mozRequestFullScreen();
  } else if(element.webkitRequestFullScreen) {
    element.webkitRequestFullScreen();
  }
}

// Launch fullscreen for browsers that support it!
launchFullScreen(document.documentElement); // the whole page
launchFullScreen(document.getElementById("videoElement")); // any individual element

Only works in IE:

window.open ("mapage.html","","fullscreen=yes");  
window.open('','_parent','');  
window.close();