Hi, im translating the article related to eval.

I'm confusing this sentence.

Code minifiers (tools used before JS gets to production, to compress it) replace local variables with shorter ones for optimization. That's usually safe, but not ifeval is used, asit may referencethem. So minifiers don't replace all local variables that might be visible fromeval. That negatively affects code compression ratio.

Could you specify what it means and them means?