这是JavaScript中最接近全屏的效果:

<script type="text/javascript">
    window.onload = maxWindow;

    function maxWindow() {
        window.moveTo(0, 0);

        if (document.all) {
            top.window.resizeTo(screen.availWidth, screen.availHeight);
        }

        else if (document.layers || document.getElementById) {
            if (top.window.outerHeight < screen.availHeight || top.window.outerWidth < screen.availWidth) {
                top.window.outerHeight = screen.availHeight;
                top.window.outerWidth = screen.availWidth;
            }
        }
    }
</script> 

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

这段代码还包括如何启用Internet Explorer 9的全屏，可能是更老的版本， 以及最新版本的谷歌Chrome。接受的答案也可以用于其他浏览器。

var el = document.documentElement
    , rfs = // for newer Webkit and Firefox
           el.requestFullscreen
        || el.webkitRequestFullScreen
        || el.mozRequestFullScreen
        || el.msRequestFullscreen
;
if(typeof rfs!="undefined" && rfs){
  rfs.call(el);
} else if(typeof window.ActiveXObject!="undefined"){
  // for Internet Explorer
  var wscript = new ActiveXObject("WScript.Shell");
  if (wscript!=null) {
     wscript.SendKeys("{F11}");
  }
}

来源:

Chrome全屏API(请注意，然而 requestFullscreen“只工作在”“[m]大多数UIEvents和鼠标事件，如点击和按下键等”，“所以它不能被恶意使用”) 如何使浏览器全屏使用F11键事件通过JavaScript

以下是我对全屏和退出全屏的完整解决方案(非常感谢上面塔的回答):

$(document).ready(function(){
$.is_fs = false;
$.requestFullScreen = function(calr)
{
    var element = document.body;

    // 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}");
        }
    }

    $.is_fs = true;    
    $(calr).val('Exit Full Screen');
}

$.cancel_fs = function(calr)
{
    var element = document; //and NOT document.body!!
    var requestMethod = element.exitFullScreen || element.mozCancelFullScreen || element.webkitExitFullScreen || element.mozExitFullScreen || element.msExitFullScreen || element.webkitCancelFullScreen;

    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}");
        }
    }    

    $(calr).val('Full Screen');    
    $.is_fs = false;
}

$.toggleFS = function(calr)
{    
    $.is_fs == true? $.cancel_fs(calr):$.requestFullScreen(calr);
}

});

// 调用:

<input type="button" value="Full Screen" onclick="$.toggleFS(this);" />

这里有一个完整的解决方案，以进入和退出全屏模式(即取消，退出，退出)

        function cancelFullScreen() {
            var el = document;
            var requestMethod = el.cancelFullScreen||el.webkitCancelFullScreen||el.mozCancelFullScreen||el.exitFullscreen||el.webkitExitFullscreen;
            if (requestMethod) { // cancel full screen.
                requestMethod.call(el);
            } else if (typeof window.ActiveXObject !== "undefined") { // Older IE.
                var wscript = new ActiveXObject("WScript.Shell");
                if (wscript !== null) {
                    wscript.SendKeys("{F11}");
                }
            }
        }

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

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

        function toggleFullScreen(el) {
            if (!el) {
                el = document.body; // Make the body go full screen.
            }
            var isInFullScreen = (document.fullScreenElement && document.fullScreenElement !== null) ||  (document.mozFullScreen || document.webkitIsFullScreen);

            if (isInFullScreen) {
                cancelFullScreen();
            } else {
                requestFullScreen(el);
            }
            return false;
        }

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();