You might want to look at humanized_time_span: https://github.com/layam/js_humanized_time_span
It's framework agnostic and fully customizable.
Just download / include the script and then you can do this:
humanized_time_span("2011-05-11 12:00:00")
=> '3 hours ago'
humanized_time_span("2011-05-11 12:00:00", "2011-05-11 16:00:00)
=> '4 hours ago'
or even this:
var custom_date_formats = {
past: [
{ ceiling: 60, text: "less than a minute ago" },
{ ceiling: 86400, text: "$hours hours, $minutes minutes and $seconds seconds ago" },
{ ceiling: null, text: "$years years ago" }
],
future: [
{ ceiling: 60, text: "in less than a minute" },
{ ceiling: 86400, text: "in $hours hours, $minutes minutes and $seconds seconds time" },
{ ceiling: null, text: "in $years years" }
]
}
humanized_time_span("2010/09/10 10:00:00", "2010/09/10 10:00:05", custom_date_formats)
=> "less than a minute ago"
Read the docs for more info.