5kyu_RGBToHexConversion.js

// 5kyu - RGB To Hex Conversion

// Description:

// The rgb() method is incomplete. Complete the method so that passing in RGB decimal 
// values will result in a hexadecimal representation being returned. The valid decimal 
// values for RGB are 0 - 255. Any (r,g,b) argument values that fall out of that range 
// should be rounded to the closest valid value.

// The following are examples of expected output values:

// rgb(255, 255, 255) // returns FFFFFF
// rgb(255, 255, 300) // returns FFFFFF
// rgb(0,0,0) // returns 000000
// rgb(148, 0, 211) // returns 9400D3

function rgb(r, g, b) {
  [r,g,b] = [r,g,b].map( a => a > 0 ? a : 0);
  [r,g,b] = [r,g,b].map( a => a > 255 ? 255 : a);
  return [r,g,b].map( a => (a > 9) ? a.toString(16) : "0" + a.toString()).join("").toUpperCase();
}