js点击某一个链接交替执行两个函数（js实现网页全屏问题）

Question

想实现的需求：
1、网页上有个“全屏显示”按钮（链接），点击全屏后执行函数fullScreen()，然后“显示全屏”二字变成“退出全屏”；
2、点击“退出全屏”执行函数exitFullScreen()，然后“退出全屏”变为“全屏显示”

function fullScreen() {
var el = document.documentElement;
var rfs = el.requestFullScreen || el.webkitRequestFullScreen ||
el.mozRequestFullScreen || el.msRequestFullScreen;
if(typeof rfs != "undefined" && rfs) {
rfs.call(el);
} else if(typeof window.ActiveXObject != "undefined") {
//for IE，这里其实就是模拟了按下键盘的F11，使浏览器全屏
var wscript = new ActiveXObject("WScript.Shell");
if(wscript != null) {
wscript.SendKeys("{F11}");
}
}
}
function exitFullScreen() {
var el = document;
var cfs = el.cancelFullScreen || el.webkitCancelFullScreen ||
el.mozCancelFullScreen || el.exitFullScreen;
if(typeof cfs != "undefined" && cfs) {
cfs.call(el);
} else if(typeof window.ActiveXObject != "undefined") {
//for IE，这里和fullScreen相同，模拟按下F11键退出全屏
var wscript = new ActiveXObject("WScript.Shell");
if(wscript != null) {
wscript.SendKeys("{F11}");
}
}
}

Answer 1

 <a href="#" onclick="return ExecuteFun(this)">全屏显示</a>
<script>
    function ExecuteFun(a) {
        var full = a.innerHTML == '全屏显示';
        full ? fullScreen() : exitFullScreen();
        a.innerHTML = full ? '退出全屏' : '全屏显示';
        return false;
    }
    function fullScreen() {
        var el = document.documentElement;
        var rfs = el.requestFullScreen || el.webkitRequestFullScreen ||
        el.mozRequestFullScreen || el.msRequestFullScreen;
        if (typeof rfs != "undefined" && rfs) {
            rfs.call(el);
        } else if (typeof window.ActiveXObject != "undefined") {
            //for IE，这里其实就是模拟了按下键盘的F11，使浏览器全屏
            var wscript = new ActiveXObject("WScript.Shell");
            if (wscript != null) {
                wscript.SendKeys("{F11}");
            }
        }
    }
    function exitFullScreen() {
        var el = document;
        var cfs = el.cancelFullScreen || el.webkitCancelFullScreen ||
        el.mozCancelFullScreen || el.exitFullScreen;
        if (typeof cfs != "undefined" && cfs) {
            cfs.call(el);
        } else if (typeof window.ActiveXObject != "undefined") {
            //for IE，这里和fullScreen相同，模拟按下F11键退出全屏
            var wscript = new ActiveXObject("WScript.Shell");
            if (wscript != null) {
                wscript.SendKeys("{F11}");
            }
        }
    }
</script>