Laptop always on charge when IN use

just wanted to ask whether is is okay to keep my laptopon charge whenever I use it. it usually dies quite fast i.e 2-3 hrs of low-medium usage so I just plug it in whenever I want to use it. is it dangerous for the computer or the battery itself?

If the charging circuitry is working properly it should not be dangerous. Some older Ni-Cad rechargeable batteries have an issue called "Voltage Depression" where not allowing them to completely discharge will reduce the time the new charge will last.

More Info:
http://www.zbattery.com/memoryeffect-pf.html