CheckForm.gs

START_TIME = "2014-01-01 08:00";
CLOSE_TIME = "2014-05-06 19:00";
MAX_RESPONSES = "20";
 
/* Initialize the form, setup triggers */
function Initialize() {
 
 deleteTriggers_();
 
 if ((START_TIME !== "") && 
 ((new Date()).getTime() < parseDate_(START_TIME).getTime())) { 
 closeForm();
 ScriptApp.newTrigger("openForm").timeBased().at(parseDate_(START_TIME)).create();
 }
 
 if (CLOSE_TIME !== "") { 
 ScriptApp.newTrigger("closeForm").timeBased().at(parseDate_(CLOSE_TIME)).create(); 
 }
 
 if (MAX_RESPONSES !== "") { 
 ScriptApp.newTrigger("checkLimit").forForm(FormApp.getActiveForm()).onFormSubmit().create();
 }
 
}
 
/* Delete any existing Triggers */
function deleteTriggers_() { 
 var triggers = ScriptApp.getScriptTriggers(); 
 for (var i in triggers) {
 ScriptApp.deleteTrigger(triggers[i]);
 }
}
 
/* Send an email to the owner when the form is opened or closed */
function informUser_(subject) {
 var formURL = FormApp.getActiveForm().getPublishedUrl();
 MailApp.sendEmail(Session.getActiveUser().getEmail(), subject, formURL); 
}
 
/* Open form to accept responses */
function openForm() {
 var form = FormApp.getActiveForm();
 form.setAcceptingResponses(true);
 informUser_("Your Google Form is now accepting responses");
}
 
/* Close form from accepting reponses */
function closeForm() { 
 var form = FormApp.getActiveForm();
 form.setAcceptingResponses(false);
 deleteTriggers_();
 informUser_("Your Google Form is no longer accepting responses");
}
 
/* If total number of responses >= limit, Close form */
function checkLimit() {
 if (FormApp.getActiveForm().getResponses().length >= MAX_RESPONSES ) {
 closeForm();
 } 
}
 
/* Parse the date/time for creating time triggers */
function parseDate_(d) {
 return new Date(d.substr(0,4), d.substr(5,2)-1, d.substr(8,2), d.substr(11,2), d.substr(14,2));
}