First Officer reported loss of the Left Hydraulic System in climb. The flight crew diverted to make a precautionary landing.

Narrative

Approaching cruise after initial climb out at FL200 we received a L HYD QTY Message. We referenced the QRH which did not have any corrective steps. The L Hydraulic Quantity was seen decreasing; with the magenta 'RF' visible. Shortly thereafter we got the L HYD SYS PRESS Message; the aircraft began a slow roll to the right. Pilot Flying turned off the left autopilot to stabilize the aircraft and then engaged the center autopilot; which operated as expected. We [requested priority handling]; got cleared direct ZZZZZ to hold as published for ZZZ ILS XX approach and began a descent to 5;000 feet. We completed QRH and began configuring to land and saw that the flaps/slats were not moving according to the indicator; though it felt like flaps were extending. We also had to perform the alternate gear extension; and decided to land at ZZZ1 since it had a 11;000 foot runway and we wanted to ensure a safe landing. With checklists complete we received vectors and landed uneventfully on Runway XY. We taxied onto Taxiway B to clear the runway and shutdown there. Loss of all left hydraulic fluid and pressure due to unknown issue.