Is there a word like "compersion" that isn't just for romantic/sexual situations?

I just saw the word "compersion" for the first time, and love it:

A feeling of joy when a loved one invests in and takes pleasure from another romantic or sexual relationship.

Is there a word that means the same thing, but not romantic/sexual? For example, when my best friend has a big win at his job, he's really happy, and I'm super happy for him too. What is the word to express that?

(Interestingly, I think the word I'm seeking is sort of the tangential opposite of schadenfreude, right?)

If you are OK with Wiktionary as a source then compersion does have the meaning you are looking for.

Noun
compersion (uncountable)
1. The feeling of joy one has experiencing another's joy, such as in witnessing a toddler's joy and feeling joy in response.
2. The feeling of joy associated with seeing a loved one love another; contrasted with jealousy.

There are a number of definitions in Wikipedia within the topic of Polyamory and therefore are predisposed to be defined in terms of sexual joy. http://en.wikipedia.org/wiki/Polyamory#Compersion

The discussion regarding that page at http://en.wikipedia.org/wiki/Talk%3ACompersion#Etymology.3F puts forward an etymology of the word offering

... he says it was created by the group via Ouija board (a device of which Kerista made extensive use for decision making), prompted when a couple of the female members were discussing positive feelings they had about their male partners with others and thought "there ought to be a word". It was not consciously invented from any roots.

see http://en.wikipedia.org/wiki/Kerista for the Keristans (who also claim polyfidelity and polyintimacy as words of their own coining - but note that these are based on Greek and Latin roots not a Ouija board)

As noted in a comment, there's no mention of it in the OED but there is (the very obsolete - 1500's) conperseyner and compercioner which are variants of comparcioner which has the definition of

One who shares a possession or inheritance with another; a copartner.

I'm not saying that is the origin of compersion but it's not too hard to extend that to simply sharing with another to cover the emotion of joy without the need for the joy to come from sexual activities.

_{Wiktionary contributors, "compersion," Wiktionary, The Free Dictionary, http://en.wiktionary.org/w/index.php?title=compersion&oldid=31307300 (accessed January 16, 2015).}

Compersion

The term is largely restricted to the polyamoury community, originating in the Kerista sect of the late 20th Century (Margot Adler's Drawing Down the Moon has some information on Kerista, though mostly incidental to discussing other groups). As defined by them compersion wasn't necessarily about sexual or romantic couplings, though they did claim that polyamory was the way (or at least a way) to live a life with compersion rather than jealousy.

It seems though to be becoming more and more restricted in meaning, as the religious claims of Kerista are less relevant to the people using it, but the question of whether jealousy will arise within a polyamorous relationship, and how to deal with it if it does, makes it a useful term of art for the polyamorous people examining their own situation.

Mudita

Another term from a religion, but Buddhism is larger and more influential than Kerista and mudita correspondingly much better known (though still relatively obscure as words go generally). Strictly it would mean "the joy available to everyone at all times, from an inner spring of joy" but often interpreted as "joy in the well being and good fortune of others".

So while it would be inaccurate to use the word this way in the context of discussing Buddhism, the word is indeed used exactly as you describe the word you are seeking.

Since compersion is both a polyamorous neologism and a word that is not recognized in mainstream dictionaries, you will have to make do with Yiddish, which (as is often the case) has just the word you're looking for. The opposit of schadenfreude is "shepping naches", which means taking joy in the success of others. It is often used in reference to parents and children, or grandparents.

Interesting. I was introduced to the word compersion by a professor friend of mine who said it meant the experience of joy at the good fortune of others. She contrasted it with envy, which her husband was writing a book about. She did not say anything about polyamory or restriction of the word to relationships. I have found definitions of compersion which fit her definition. I have also heard from friends in the mental health profession that they were familiar with the word compersion, used as I was told.

As a wordsmith, I am pleased to think that English has at least one word to stand against envy and jealousy, whose meanings we are all too familiar with.

I believe compersion describes a real emotion, and I have been and continue to be glad to have a word for the warm feelings of gratitude and joy I feel at the success, or good luck of others whom I value.