在较新的浏览器中，如Chrome 15, Firefox 10, Safari 5.1, IE 10，这是可能的。根据浏览器设置，旧版本的IE也可以通过ActiveX实现。

以下是如何做到这一点:

function requestFullScreen(element) {
    // Supports most browsers and their versions.
    var requestMethod = element.requestFullScreen || element.webkitRequestFullScreen || element.mozRequestFullScreen || element.msRequestFullScreen;

    if (requestMethod) { // Native full screen.
        requestMethod.call(element);
    } else if (typeof window.ActiveXObject !== "undefined") { // Older IE.
        var wscript = new ActiveXObject("WScript.Shell");
        if (wscript !== null) {
            wscript.SendKeys("{F11}");
        }
    }
}

var elem = document.body; // Make the body go full screen.
requestFullScreen(elem);

用户显然需要首先接受全屏请求，并且不可能在页面加载时自动触发此请求，它需要由用户触发(例如。一个按钮)

阅读更多信息:https://developer.mozilla.org/en/DOM/Using_full-screen_mode

screenfull.js试试。这是一个很好的跨浏览器解决方案，应该也适用于Opera浏览器。

JavaScript全屏API跨浏览器使用的简单包装器，它允许您将页面或任何元素显示为全屏。消除了浏览器实现的差异，所以您不必这样做。

演示。

简单的例子:http://www.longtailvideo.com/blog/26517/using-the-browsers-new-html5-fullscreen-capabilities/

<script type="text/javascript">
  function goFullscreen(id) {
    // Get the element that we want to take into fullscreen mode
    var element = document.getElementById(id);

    // These function will not exist in the browsers that don't support fullscreen mode yet, 
    // so we'll have to check to see if they're available before calling them.

    if (element.mozRequestFullScreen) {
      // This is how to go into fullscren mode in Firefox
      // Note the "moz" prefix, which is short for Mozilla.
      element.mozRequestFullScreen();
    } else if (element.webkitRequestFullScreen) {
      // This is how to go into fullscreen mode in Chrome and Safari
      // Both of those browsers are based on the Webkit project, hence the same prefix.
      element.webkitRequestFullScreen();
   }
   // Hooray, now we're in fullscreen mode!
  }
</script>

<img class="video_player" src="image.jpg" id="player"></img>
<button onclick="goFullscreen('player'); return false">Click Me To Go Fullscreen! (For real)</button>

这个函数非常好用

function toggle_full_screen()
{
    if ((document.fullScreenElement && document.fullScreenElement !== null) || (!document.mozFullScreen && !document.webkitIsFullScreen))
    {
        if (document.documentElement.requestFullScreen){
            document.documentElement.requestFullScreen();
        }
        else if (document.documentElement.mozRequestFullScreen){ /* Firefox */
            document.documentElement.mozRequestFullScreen();
        }
        else if (document.documentElement.webkitRequestFullScreen){   /* Chrome, Safari & Opera */
            document.documentElement.webkitRequestFullScreen(Element.ALLOW_KEYBOARD_INPUT);
        }
        else if (document.msRequestFullscreen){ /* IE/Edge */
            document.documentElement.msRequestFullscreen();
        }
    }
    else
    {
        if (document.cancelFullScreen){
            document.cancelFullScreen();
        }
        else if (document.mozCancelFullScreen){ /* Firefox */
            document.mozCancelFullScreen();
        }
        else if (document.webkitCancelFullScreen){   /* Chrome, Safari and Opera */
            document.webkitCancelFullScreen();
        }
        else if (document.msExitFullscreen){ /* IE/Edge */
            document.msExitFullscreen();
        }
    }
}

要使用它，只需调用:

toggle_full_screen();

试试这个脚本

<script language="JavaScript">
function fullScreen(theURL) {
window.open(theURL, '', 'fullscreen=yes, scrollbars=auto' );
}
</script>

从脚本调用使用以下代码，

window.fullScreen('fullscreen.jsp');

或者用超链接使用这个

<a href="javascript:void(0);" onclick="fullScreen('fullscreen.jsp');"> 
Open in Full Screen Window</a>

既然全屏api越来越广泛，而且似乎越来越成熟，为什么不试试Screenfull.js呢?我昨天第一次使用它，今天我们的应用程序在(几乎)所有浏览器中真正全屏!

确保它与CSS中的:fullscreen伪类相结合。详见https://www.sitepoint.com/use-html5-full-screen-api/。