weird result while reducing saturation only of color using expression

I wanted to reduce only the saturation to 50% (0.5) of color and something weird happens.

Method 01

myHsl=rgbToHsl([1,0,0,1]);
myHsl[1]=0.5
hslToRgb([myHsl[0],myHsl[1],myHsl[2],1])

Method 2

function hexToRgb(h){
c = parseInt(h,16);
r = c >> 16;
g = (c & 0x00ff00) >> 8;
b = c & 0xff;
return [r,g,b,255]/255;
}

myRgb = hexToRgb("FF0000");
myHsl=rgbToHsl(myRgb );
myHsl[1]=0.5;
myUpdatedHsl=[myHsl[0],myHsl[1],myHsl[2],1];
hslToRgb(myUpdatedHsl)

Both method doesn't work as expected (attached)

I have attached pictures of results

please help.