Because we are all human, JunOS provides a very cool feature to work around the human limitation: a setting that dumps your config to an FTP server when you commit the config. Here's how you do it:
[edit]
root@branch-3200# edit system archival configuration
[edit system archival configuration]
root@branch-3200# transfer-on-commit;
[edit system archival configuration]
root@branch-3200# archive-sites {
[edit system archival configuration archive-sites]
"ftp://username:password@myftphost.example.com";
Of course, the ability to save your configuration is not terribly useful without the ability to restore it, so JunOS provides that ability, as well (natch):
[edit]
root@branch-3200# edit system archival configuration
[edit system archival configuration]
root@branch-3200# load merge ftp://username:password@myftphost.example.com/branch-3200.conf.gz_20140410_111217
load complete
[edit system archival configuration]
root@branch-3200#