The snippet uses the native Javascript function so it should be more efficient then for instance using arithmetic or looped bitwise operations etc.

Examples:

// convert the decimal 10 to hex
Math.base(10, 16); // 'a'

// convert the hex 'a' to decimal
Math.base('a', 10, 16); // 10

// convert the decimal 10 to binary
Math.base(10, 2); // '1010'

// convert the hex 'a' to decimal
Math.base('a', 2, 16); // 1010

[Base conversion in JavaScript][1]

[1]: http://www.bucabay.com/web-development/base-conversion-in-javascript/ "Base conversion in JavaScript"

Math.base = function base(n, to, from) {
     return parseInt(n, from || 10).toString(to);
}