15.8.2.3 Math.asin(x)

number Math.asin(x:number|mixed)

Return arc sine of x.

Result expressed in radians! In range of -π/2 to +π/2.

Math.asin = function(x){
x = ToNumber(x);
if (isNaN(x)) return NaN;
if (x > 1) return NaN;
if (x < -1) return NaN;
if (x === +0) return +0;
if (x === -0) return -0;
return Math.asin(x);
}