15.8.2.9 Math.floor(x)

number Math.floor(x)

Return the integer part of x, removing all decimal digits.

Math.floor = function(x){
x = ToNumber(x);
if (isNaN(x)) return NaN;
if (x === +0) return +0;
if (x === -0) return -0;
if (x === +Infinity) return +Infinity;
if (x === -Infinity) return -Infinity;
if (x > 0 && x < 1) return +0;
return Math.floor(x);
// return -Math.ceil(-x);
// return ~~x;
// return x|0;
// etc...
}