floor

Returns the largest double less than or equal to a, and equal to a mathematical integer. If a is ##NaN or ##Inf or ##-Inf or already equal to an integer => a If a is less than zero but greater than -1.0 => -0.0 Note that if a is `nil` then an exception will be thrown. This matches Clojure, rather than js/Math.floor See: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Math/floor