I am curious why we use cache[n] in this code [duplicate]

Question

I am new to JS and came across this code:

let cache={};

function memoizedAddTo80(n) {
    if (n in cache) {
        return cache[n]
    } else {
        cache[n]= n+80;
        return cache[n]
    }
}

The question is what is cache[n]?, I mean, why do we use [n] after cache. Is cache[n] equal to cache.n Or???

Answer 1

n is a variable. Consider:

var n = "foo";
return cache[n];

This would be equivalent to cache.foo