Math.log2()

The Math.log2() function returns the base 2 logarithm of a number, that is

$$\forall x > 0, \mathtt{\operatorname{Math.log2}(x)} = \log_2(x) = \text{the unique} ; y ; \text{such that} ; 2^y = x$$

x

A number.

The base 2 logarithm of the given number. If the number is negative, NaN is returned.

If the value of x is less than 0, the return value is always NaN.

Because log2() is a static method of Math, you always use it as Math.log2(), rather than as a method of a Math object you created (Math is not a constructor).

This function is the equivalent of Math.log(x) / Math.log(2). For log2(e) use the constant Math.LOG2E which is 1 / Math.LN2.

This Polyfill emulates the Math.log2 function. Note that it returns imprecise values on some inputs (like 1 << 29), wrap into Math.round() if working with bit masks.

if (!Math.log2) Math.log2 = function(x) {
  return Math.log(x) * Math.LOG2E;
};

• Polyfill of Math.log2 in core-js
• Math.exp()
• Math.log()
• Math.log10()
• Math.log1p()
• Math.pow()