restart cron daemon

I am using javascript/ bonescript to write to the crontab file (with writeTextFile).

But nothing changes because (I think ) the daemon needs to be restarted.

I can bring down and back up the daemon from the shell but I want to do it from a webpage (i.e. javascript with bonescript).

any thoughts?

Which file do you edit ???
/var/spool/cron/* should not be edited except with crontab -e
/etc/crontab should only be edited by root

But you could write your stuff in a script and call that script every
minute with crontab:

#!/bin/bash
i=$(date +%M)
if [ $i = "30" ]; then
        date >> date.txt
        # add your code here
fi

will run your code always at half past.....