EN

# JavaScript - example, how to calculate logarithm with custom base?

4
points

In this article, we would like to show how to __calculate logarithm__ for __specific base__ using __JavaScript__.

Practical example:

```
// ONLINE-RUNNER:browser;
function calculateLogarithm(base, x) {
var a = Math.log(x);
var b = Math.log(base);
return a / b;
}
// Logarithm with custom base:
// base x y
console.log( calculateLogarithm( 2, 2 ) ); // 1
console.log( calculateLogarithm( 2, 4 ) ); // 2
console.log( calculateLogarithm( Math.E, Math.E ) ); // 1
console.log( calculateLogarithm( 3, 9 ) ); // ~2
console.log( calculateLogarithm( 3, 81 ) ); // ~4
console.log( calculateLogarithm( 10, 10 ) ); // 1
```

Note: read this article to see

`Math.log()`

method documentation.