If you don't mind setting the function on instances at construct time, you can use ES2016 class properties: class x { a = wrapFunction(function() {})

If you don't mind setting the function on instances at construct time, you can use ES2016 class properties: class x { a = wrapFunction(function() {}) } This kind of use case is pretty well covered by ES2016 decorators as well (they're a bit more general as they act on property descriptors, not just values): class x { @functionWrapper a() {} }