iPad Air battery

Hi. I have the latest iPad Air and have a query about the battery. Where I sit and work I usually have iPad on in background and am near a plug for charging. If I am constantly streaming on it am I best having it plugged in all the time because I can, or am I best not and let the battery do the normal battery cycles? Obviously there will be times I use it without it being plugged in, but wonder will it do any harm having it plugged in for long periods when I can.