Driver Expressions for Animations in Blender – #frame

I need to create the “connection lines” that represent the energy flow. I have a thin cylinder mesh, and thanks to the shader from the image below I can slide the glowing effect along it. In the circled value I can type #frame and it perfectly animates the flow in Blender. But unfortunately, it doesn’t work in Verge3D. I also tried to set up this value via puzzle but it requires a number input and rejects the # symbol.

I know I can do that, but this solution doesn’t create a perfect loop. Also, in other shaders, I would like to use the #frame instead of keyframes, so I’m trying to figure out if it’s possible to use it in Verge.
The problem with keyframes is that they end at some point. And even if the animation is looped, when the keyframes end and the animation is played again, there is a sudden “jump” in the visual effect (when it comes back to the first frame). I try to avoid this “jump”, so the #frame solution seems to be the best. But I guess I need to find another walkaround unless someone knows the answer on how to use “#frame” in Verge.