//// [enumMapBackIntoItself.ts] enum TShirtSize { Small, Medium, Large } var mySize = TShirtSize.Large; var test = TShirtSize[mySize]; // specifically checking output here, bug was that test used to be undefined at runtime test + '' //// [enumMapBackIntoItself.js] var TShirtSize; (function (TShirtSize) { TShirtSize[TShirtSize["Small"] = 0] = "Small"; TShirtSize[TShirtSize["Medium"] = 1] = "Medium"; TShirtSize[TShirtSize["Large"] = 2] = "Large"; })(TShirtSize || (TShirtSize = {})); var mySize = TShirtSize.Large; var test = TShirtSize[mySize]; // specifically checking output here, bug was that test used to be undefined at runtime test + '';