Air carrier First Officer reported during cruise flight experiencing a cockpit window shattering resulting in the flight crew diverting to another airport where they landed safely.

Narrative

Prior to departure; I noted some scratches on the windshield that could potentially be a structural issue inflight while waiting to depart from ZZZ to ZZZ1 in the middle of the afternoon. Maintenance came to inspect it and deemed it safe to fly as long as it wasn't going to be a distraction for me as I was the pilot flying that leg. I deemed it wasn't an issue for me as I could see outside with no issues or obstructions. We departed on time and were about halfway through the flight when we suddenly heard a loud popping sound. I took my eyes off the charts; that I was briefing quietly to prepare to brief my Captain; to look at a windshield that completely shattered; but remained intact. Simultaneously; the windshield heat caution message appeared on our EICAS Display. I immediately put my shoulder harnesses on and called for the QRH checklist on shattered windshield while I took over radios and flight controls to keep ATC informed of our situation. I requested a lower altitude based on the QRH checklist recommendation while the Captain called Dispatch and Maintenance via AIRINC. The result of the discussion was to divert to ZZZ2 to swap out planes and allow Maintenance to work out the problem and repair or replace the windshield. I requested to divert to ZZZ2 through ATC; and we were given clearance direct to the airport. We were 15 minutes away from ZZZ2 at this point and my Captain called the flight attendants to notify them of the situation while I prepared the aircraft for arrival into ZZZ2 airport. Captain made a PA to the passengers about our plan while I continued to coordinate with ATC. Once he was done notifying the passengers in the back. We returned back to briefing the arrival and approach into ZZZ2 and determined it was a safe plan to transfer controls to the Captain for the approach and landing portion of the flight as it was critical to have clear visual of the airport and runway environment with a clear windshield. We transferred controls and Autopilot controls and I kept control of the radios for the approach and arrival. We landed on XXR and completed the landing portion of the QRH while taxiing into the gate. Passengers deplaned to move to another airplane while we relinquished the plane with the shattered windshield to Maintenance and gave them details of the event. We switched to a new aircraft and continued to our destination with all passengers. The same crew that experienced this event had flown the same aircraft twice prior to encountering this event. Cause: Uncertain of the cause as focal point of the shatter occurred in a separate area away from the windshield scratches and there was no write ups about previous bird strikes on the FO (First Officer) side windshield. We had the windshield heat turned on the low switch setting during the After Takeoff Checklist. Discussed it with Maintenance as to why it happened; and we could not come up with anything conclusive at that moment.Suggestions: Difficult to say without knowing the exact cause of the shatter unless it is because the windshield hadn't been replaced in time. We had the heat running; it was working just fine for the 2 flights leading to the 3rd flight when the event occurred; and there were not previous write ups that would lead us to be wary of the FO side windshield. Certainly inspecting the windshield's structural integrity is always a good recommendation; especially when it comes to older aircraft in our fleet. There's no telling when a windshield could structurally fail unless there was documentation provided to show when it needs to be replaced.