gistfile1.js

var rectangle = { x     : 0
                , y     : 0
                , w     : 10
                , h     : 10
                , hugh  : hue        // 120
                , satch : saturation // '50%'
                , lite  : light }    // '50%'
 
  , drawRec = function(recObj, modifyColor) {
      
      // do some canvas setup stuff, then set the fill color...
      if (modifyColor === 'undefined'){
        canvasContext.fillStyle = 'hsl(' + recObj.hugh + ',' + recObj.satch + ',' + recObj.lite + ')';
      }
      else {
        var moddedSatch = (parseInt(recObj.satch) - 10 ) + '%'
          , moddedLite  = (parseInt(recObj.satch) - 10 ) + '%'
        canvasContext.fillStyle = 'hsl(' + recObj.hugh + ',' + moddedSatch + ',' + moddedLite + ')';
      }
 
      // draw some stuff
    }