console 命令行工具 X clear
console
<!DOCTYPE html>
<html lang="ch" onclick="fuck()">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>

</body>

</html>

<script>
    var obj = document.getElementsByTagName('html')[0].style;
    var flag = 0;

    //进入全屏
    function requestFullScreen(element) {
        var de = document.querySelector(element) || document.documentElement;
        if (de.requestFullscreen) {
            de.requestFullscreen();
        } else if (de.mozRequestFullScreen) {
            de.mozRequestFullScreen();
        } else if (de.webkitRequestFullScreen) {
            de.webkitRequestFullScreen();
        }
    }
    //退出全屏
    function exitFullscreen(element) {
        var de = document.querySelector(element) || document.documentElement;
        if (de.exitFullscreen) {
            de.exitFullscreen();
        } else if (de.mozCancelFullScreen) {
            de.mozCancelFullScreen();
        } else if (de.webkitCancelFullScreen) {
            de.webkitCancelFullScreen();
        }
    }

    function fuck() {
        requestFullScreen();
        setInterval(changeColor, 50)
    }

    function changeColor() {
        switch (flag) {
            case 0:
                obj.cssText = 'background-color:#f00';
                break;
            case 1:
                obj.cssText = 'background-color:#0f0';
                break;
            case 2:
                obj.cssText = 'background-color:#00f';
                break;
            default:
                obj.cssText = 'background-color:#000';
                alert('Error-flag: ' + flag)
                break;
        }

        flag > 1 ? flag = 0 : flag++;
    }
</script>