Math.LOG2E
syntax: 
Math.LOG2E 
description: 
The number value for the base 2 logarithm of e, the base of the natural logarithms. This value is represented internally as approximately 1.4426950408889634. The value of Math.LOG2E is approximately the reciprocal of the value of Math.LN2.

example: 
var n = Math.LOG2E; 