You can get the ID of the first running experiment (assuming you have one), and then the variation index (e.g., 0, 1, 2), name, and ID:
var experimentID = window['optimizely'].data.state.activeExperiments[0];
var variationIndex = window['optimizely'].data.state.variationMap[experimentID];
var variationName = window['optimizely'].data.state.variationNamesMap[experimentID];
var variationID = window['optimizely'].data.state.variationIdsMap[experimentID];