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<!DOCTYPE html>
<html>
  <head>
    <meta charset="utf-8">
    <title>RGB to HEX (and vice versa) converter</title>
    <link rel="stylesheet" href="http://cdnjs.cloudflare.com/ajax/libs/normalize/3.0.0/normalize.min.css">
    <style>
      body{
        color: #222;
        font-family: "Segoe UI", sans-serif;
      }
      #main {
        margin: 10% auto;
        max-width: 300px;
      }
      input[type="text"] {
        padding: 10px;
        width: 100%;
        outline: 0;
        border: 0;
        border-bottom: 1px dashed;
        background: inherit;
        text-shadow: 0 1px 0 #f0f0f0;
        font-size: 18px;
      }
      ::-webkit-input-placeholder { color: #a9a9a9; }
      :-moz-placeholder { color: #a9a9a9; }
      ::-moz-placeholder { color: #a9a9a9; }
      :-ms-input-placeholder { color: #a9a9a9;}
    </style>
  </head>
  <body>
    <div id="main">
      <p><input id="rgb" type="text" placeholder="rgb(255, 255, 255)"></p>
      <p><input id="hex" type="text" placeholder="#ffffff"></p>
    </div>
    <script>
      (function() {
        "use strict";

        var inputRgb = document.getElementById("rgb"),
          inputHex = document.getElementById("hex"),
          converter = {
            // help: http://stackoverflow.com/questions/5623838/rgb-to-hex-and-hex-to-rgb

            toHex: function() {
              function componentToHex(c) {
                var hex = parseInt(c).toString(16);
                return hex.length == 1 ? "0" + hex : hex;
              }
              var rgb = /^rgb\((\d{1,3}),\s*(\d{1,3}),\s*(\d{1,3})\)$/.exec(inputRgb.value);
              inputHex.value = rgb ? "#" + componentToHex(rgb[1]) + componentToHex(rgb[2]) + componentToHex(rgb[3]) : "";
              converter.changeBgColor(inputRgb.value);
            },

            toRgb: function() {
              // expand shorthand form (e.g. "03f") to full form (e.g. "0033ff")
              var hex = inputHex.value.replace(/^#?([a-f\d])([a-f\d])([a-f\d])$/i, function(m, r, g, b) {
                return r + r + g + g + b + b;
              }),
                result = /^#?([a-f\d]{2})([a-f\d]{2})([a-f\d]{2})$/i.exec(hex);
              inputRgb.value = result ? "rgb(" + [parseInt(result[1], 16), parseInt(result[2], 16), parseInt(result[3], 16)].join(", ") + ")" : "";
              converter.changeBgColor(inputHex.value);
            },

            changeBgColor: function(color) {
              document.body.style.backgroundColor = color;
            }
          };

        inputRgb.addEventListener("input", converter.toHex, false);
        inputHex.addEventListener("input", converter.toRgb, false);

      }());
    </script>
  </body>
</html>

Jsbin - http://jsbin.com/fokayomo/1/

share|improve this question

1 Answer 1

up vote 5 down vote accepted

Two things jump out at me.

  1. Decouple from the HTML elements.

    var inputRgb = document.getElementById("rgb"),
        inputHex = document.getElementById("hex"),
    

    I would do something like:

    function RGB2Hex (inputRgb, inputHex){
        var converter = {
            toHex: ...
            toRGB: ...
        };
    
        inputRgb.addEventListener("input", converter.toHex, false);
        inputHex.addEventListener("input", converter.toRgb, false);
    
        return converter;
    }
    
    // Usage:
    var mainHexConversion = new RGB2Hex(document.getElementById("rgb"), document.getElementById("hex"));
    var secondHexConversion = new RGB2Hex(document.getElementById("mini-rgb"), document.getElementById("mini-hex"));
    
  2. keep the background colour changing code outside the converter.

    function RGB2Hex (inputRgb, inputHex, onColourChange)
    {
       var converter = {
            toHex: ...
            toRGB: ...
            colourChanged: function(colourValue){
                if(typeof onColourChanged == "function")
                {
                    onColourChange(colourValue);
                }
            }
        };
    }
    
    // Usage: 
    var mainHexConversion = new RGB2Hex(
        document.getElementById("rgb")
        , document.getElementById("hex")
        , function(color)
        {
          document.body.style.backgroundColor = color;
        }
    );
    
share|improve this answer
    
would you please edit your answer with the final code... thanks. –  annn Mar 7 at 8:13
    
I think my answer is not complete enough to have "the final code". I encourage you to read it and take the parts from it as you like. –  James Khoury Mar 8 at 13:26
    
thanks anyways. I'll make use of your suggestions. –  annn Mar 9 at 11:47

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