Nice.
Just in case you need time handling later on: msg.metadata.time is a text string. Programming languages cannot automatically tell the difference from "2020-07-04T15:38:25.418218894Z" to, say, "Hello World". So you’ll first need to tell JavaScript the text denotes some date and time. For the ISO 8601 formatted text that TTN gives you that’s easy:
var previous = new Date("2020-07-04T15:38:25.418218894Z");
var current = new Date(msg.metadata.time);
var milliseconds = current - previous;
var seconds = milliseconds / 1000;
var hours = seconds / 3600;
Aside: this is not called “latency”. Latency is the time it takes for a packet to get from node to gateway (this is the calculated air time), then from gateway(s) to the network server and other TTN components, and finally up to your Node-RED application server. That kind of delay you cannot calculate as you don’t know anything about the accuracy of the clocks in all those systems. You may even get negative values then. But that’s not what you wanted anyway. “Interval” is a much better name!
Another aside, please don’t post code as images: it just adds a lot of unrelated details (even inactive code and comments; why even bother the readers with that?), it’s hard to view on small devices, it’s not searchable, and one cannot copy code out of an image.
Thanks for posting the solution!
The support and maintenance for this SDK has been discontinued, it is not recommended to use the SDK for new projects.
