I don't agree with this style.<p>`var` is broken. Don't try to find a use-case for it. Just don't use it.<p>It would be nicer to have real, deep immutability, but `const` isn't it. Therefore, use it for what it actually is, not what you wish it was. If you don't intend to reassign a reference, then mark the reference constant. That's it.<p>It may be surprising, but it's quite easy to write JS where almost every declaration is `const`. When every mundane variable is `const`, then the more complex initializations/data flows/accumulators really requiring `let` stand out, which is very useful for reviewing code ("let" = "warning: there may be an `else` or missing `switch` case that will leave that undefined").<p>Because `const` requires to be initialized at the time of definition, you know the variable is valid for its entire lifetime. When you find its value was wrong, there's only one place where the value could have come from (you don't need to comb the function to look for reassignments).