理解不是很透

var secret_key = "1368921";//按键组合数字键
var check_key = "";//校验键
var enter_url = "/activity/act_back2school/index.do";//要去的地址
function add_count(i){
check_key += "" + i;
compare_key();
}
function compare_key(){
if(check_key.length == secret_key.length){
if(secret_key == check_key){
window.location.href = enter_url;
}else{
check_key = check_key.substring(1,check_key.length);
}
}
}
for(var i = 0 ; i < 10 ; i++){
evtMap['number' + i] = function(k){
return function(){
add_count(k);
}
}(i);
}