Convert RGBA on white to RGB

index.js

// taken from here and made to work
// 


var debug = false;

//var rgbaColor = 'rgba(1,12,123,0.33)';
var rgbaColor = 'rgba(247, 224, 153, 0.247)';
// var rgbaColor = '#999';
// var rgbaColor = 'rgb(30, 20, 200)';



var rgbColor = convertRGBAtoRGBIfNeeded(rgbaColor)

console.log('RGB', rgbColor)


var rgbaElement = document.getElementById("rgba");
var rgbElement = document.getElementById("rgb");
setColor(rgbaElement, rgbaColor)
setColor(rgbElement, rgbColor)

function setColor(element, color) {
  if (!element) return;
  element.style.backgroundColor = color;
}

function convertRGBAtoRGBIfNeeded(colorCssString) {
  
  

  var isRGBA = function(colorCssString) {
    return colorCssString.match(/rgba/gi);
  }

  if (!isRGBA(colorCssString)) return colorCssString;

  var colorArray = colorCssString.match(/\d+\.*\d*/g); 
  if (debug) console.log(colorArray);
  
  var rgb = colorCssString.match(/\d+\.*\d+/g);
  if (debug) console.log('rgb:', rgb);

  var Source = {};
  Source.R = colorArray.shift()/255;
  Source.G = colorArray.shift()/255;
  Source.B = colorArray.shift()/255;
  Source.A = colorArray.shift()/1;
  if (debug) console.log(colorArray);
  if (debug) console.log(Source);
  
  var BGColor = {
    R: 1,
    G: 1,
    B: 1
  };

//    Credits to:
//    https://stackoverflow.com/questions/2049230/convert-rgba-color-to-rgb
  var Target = {};
  Target.R = parseInt(255 * (((1 - Source.A) * BGColor.R) + (Source.A * Source.R)));
  Target.G = parseInt(255 * (((1 - Source.A) * BGColor.G) + (Source.A * Source.G)));
  Target.B = parseInt(255 * (((1 - Source.A) * BGColor.B) + (Source.A * Source.B)));
  
  if (debug) console.log(Target);
  
  var rgbColor2 = 'rgb(' + Target.R + ',' + Target.G + ',' + Target.B + ')'; 
  
  return rgbColor2;
  

  
}