Islamic dietary laws aren't as strict as people are saying in the comments. Chocolate is halal in general. There is no need to investigate whether or not a chocolate is halal. If you want to be extra careful, read the ingredients. Unless it has meat or some alcohol product in it like liquor or wine, there's nothing forbidden about chocolate. It's possible that gelatin is not halal, but I don't think that's a typical ingredient in chocolate. (In gummies, yes.)