window.onmouseleave = window.onblur = window.onmouseout = document.onmouseleave = document.onblur = document.onmouseout = document.body.onmouseleave = document.body.onblur = document.body.onmouseout = onmouseleave = onblur = onmouseout = function(){
    //这里可以加入切屏警告代码，一般为了防止学生误操作，可以加入切屏第几次的提示，剩余多少次(我们一般就用3次），3次之后就彻底关掉网页，或者自动提交考试内容
};

防止考生复制考试题目或者答案内容

window.onselectstart = document.onselectstart = document.body.onselectstart = onselectstart = document.querySelector("html").onselectstart = function(){
    //这里用 return false 来防止选中复制内容，也可以写复制其他禁止考试内容
};
 
防止考生用右键菜单复制内容

window.oncopy = window.onpaste = document.oncopy = document.onpaste = document.body.oncopy = document.body.onpaste = oncopy = onpaste = function(){
    //这里用 return false 来防止复制粘贴内容，也可以写复制其他禁止考试内容
};

window.oncontextmenu = document.oncontextmenu = document.body.oncontextmenu = oncontextmenu = document.querySelector("html").oncontextmenu = function(){
    //return false 防止考生使用右键菜单
};

针对ctrl+shift+C以及F12做了屏蔽

 window.onkeyup = window.onkeydown = window.onKeyPress = document.onkeyup = document.onkeydown = document.onKeyPress = document.body.onkeyup = document.body.onkeydown = document.body.onKeyPress = onkeyup = onkeydown = onKeyPress = function(){
    //防止学生使用快捷键组合
};