Child support lasts until the children are age 18, or if still in high school, 19. (Unless you have a special needs child, in which case it could be longer).
Spousal support depends on a variety of factors. In a short term marriage (less than 10 years), Los Angeles County Courts will generally award 1/2 the length of the marriage. However, if there is a temporary order for support, and no termination date, this order will continue indefinitely. Be careful if you are the payor – it is easy for the recipient to “drag out” the divorce case and continue to receive alimony beyond half the length of the marriage.