如何防止用户离开javascript中的当前窗口？

Question

I am developing application, where user has to write certification exam online. Once user clicks start exam button, I am opening popup window to give exam. But we should not allow user to move away from this window(To prevent him from copying answer by googling in another window). User should not be able to move away from active window in any way like pressing ALT+TAB (or) WINDOWS+D.

Basically, in javascript, we need to prevent user to move away from current window in all possible ways. How to do it?

Answer 1

Preventing users from leaving your site, is all a spamer needs. Thats why it is impossible. The only thing you can do, is to check if the user moved away. This will stop the js execution: (See Detect if browser tab is active or user has switched away for original code)

 var vis = (function(){ var stateKey, eventKey, keys = { hidden: "visibilitychange", webkitHidden: "webkitvisibilitychange", mozHidden: "mozvisibilitychange", msHidden: "msvisibilitychange" }; for (stateKey in keys) { if (stateKey in document) { eventKey = keys[stateKey]; break; } } return function(c) { if (c) document.addEventListener(eventKey, c); return !document[stateKey]; } })();

vis(function(){
if(vis()==false){
alert("You left the site. You try to cheat");
//do sth else
}
});