Help with Calculator!

Hey all,

I CANNOT figure out my calculator and I feel like I’ve gotten so lost in trying to figure it out at this point, I’m getting further away.

What I CANNOT (and I mean cannot figure out) is how to ONLY get the last operator if more than one pushed (e.g. 2 + 3 * - + 5 ----> should return 2 + 3 + 5)

Any help is GREATLY appreciated! Below is the link to my codepen.

Calculator Codepen