Calculates the n-base logarithm of a number.
JavaScript provides methods to calculate the natural, base-2 and base-10 logarithm, i.e., Math.log(), Math.log2() and Math.log10() respectively.
... and that's it! With this method you can calculate an n-base logarithm.
Math.logn(x,n)-$\log_n x$
const four = Math.logn(81,3);
// the base-3 logarithm of 81
console.log(four);
// 4