JAVASCRIPT

rgb to hex js

const rgb2hex = (rgb) => `#${rgb.match(/^rgb((d+),s*(d+),s*(d+))$/).slice(1).map(n => parseInt(n, 10).toString(16).padStart(2, '0')).join('')}`

// Use as you wish...
console.log(rgb2hex('rgb(0,0,0)'))
console.log(rgb2hex('rgb(255, 255, 255)'))
console.log(rgb2hex('rgb(255,0,0)'))
console.log(rgb2hex('rgb(38, 170, 90)'))
 Run code snippet

hex to rgba in js

hexToRGB(hex: string, alpha: string) {

  const r = parseInt(hex.slice(1, 3), 16);
  const g = parseInt(hex.slice(3, 5), 16);
  const b = parseInt(hex.slice(5, 7), 16);

  if (alpha) {
    return `rgba(${r}, ${g}, ${b}, ${alpha})`;
  } else {
    return `rgb(${r}, ${g}, ${b})`;
  }
}

javascript hex color to rgba

//If you write your own code, remember hex color shortcuts (eg., #fff, #000)

function hexToRgbA(hex){
    var c;
    if(/^#([A-Fa-f0-9]{3}){1,2}$/.test(hex)){
        c= hex.substring(1).split('');
        if(c.length== 3){
            c= [c[0], c[0], c[1], c[1], c[2], c[2]];
        }
        c= '0x'+c.join('');
        return 'rgba('+[(c>>16)&255, (c>>8)&255, c&255].join(',')+',1)';
    }
    throw new Error('Bad Hex');
}

hexToRgbA('#fbafff')

/*  returned value: (String)
rgba(251,175,255,1)
*/

rgb to hex js

function rgb(r, g, b){
  // complete this function 
  return hexC(r)+hexC(g)+hexC(b)
}
function hexC(v){
  if(v>255){
    v=255
  }else if(v<0){
    v=0
  }
  let a=v%16;
  let b=Math.floor(v/16);
  return hmaps[b]+hmaps[a]
  }
let hmaps={
  0:'0',1:'1',2:'2',3:'3',4:'4',5:'5',6:'6',7:'7',8:'8',9:'9',10:'A',11:'B',12:'C',13:'D',14:'E',15:'F'
  }