Any way to specify the base of math.log() in javascript?

Question

I need a log function in my javascript but it needs to be base 10, I can't see any listing for this so I'm assuming it's not possible... any math wizards out there know of an approach for this? Or maybe I'm missing something and there is a way?

Answer 1

function log10(val) {
  return Math.log(val) / Math.log(10);
}

Answer 2

Easy, just change the base by dividing by the log(10). There is even a constant to help you

Math.log(num) / Math.LN10;

which is the same as:

Math.log(num) / Math.log(10);

Answer 3

Math.log10 = function(n) {
    return (Math.log(n)) / (Math.log(10));
}

Then you can do

Math.log10(your_number);

NOTE: Initially I thought to do Math.prototype.log10 = ... to do this, but user CMS pointed out that Math doesn't work this way, so I edited out the .prototype part.

Answer 4

You can simply divide the logarithm of your value, and the logarithm of the desired base, also you could override the Math.log method to accept an optional base argument:

Math.log = (function() {
  var log = Math.log;
  return function(n, base) {
    return log(n)/(base ? log(base) : 1);
  };
})();

Math.log(5, 10);