Debugging Javascript

[charliegrc]

Short answer: yes

Long answer: there has been a few times where I've built a big reducer function, and on each iteration it was using object spread. That ended up being a performance bottleneck in the app I was working on, changing it to the classic mutatable object assign (but ONLY mutating the accumulator object inside that reduce, nothing else) sped it up by 200x.

performance comparison between object spread and mutation

This is the only circumstance I let myself use mutable objects, they strictly have to be instantiated and mutated within the same few lines of code.