Convert time range to epoch time

Grafana
3

With v6.7, the following works fine for me as mentioned in how-to-dynamic-get-system-time-range-variable:

let tr = angular.element('grafana-app').injector().get('timeSrv').timeRange();
let from = new Date(tr.from._d).toISOString();
let to = new Date(tr.to._d).toISOString();