or this (for automation)
The problem with this method is that now the script file will never be cached, or rather, reloaded every time a user visits the page, unless he loses interest, goes away and then comes back to check out what’s new, and than realizes, like “Wow…it’s still the same second?! Cause I noticed the script file hasn’t reloaded. Man, I left like ages ago. I should really lay of the E.” So we never really used this and just let nature take it’s course. But then it came to me…
This function returns the change time of a file, the script.js file in this case. Ladies and gentleman, the page will from now forth automatically force reload of a script file only when it has been changed.