invertDivColor.js

$(document).ready(function() {
 function invertColor(hexTripletColor) {
    var color = hexTripletColor;
    color = color.substring(1);           // remove #
    color = parseInt(color, 16);          // convert to integer
    color = 0xFFFFFF ^ color;             // invert three bytes
    color = color.toString(16);           // convert to hex
    color = ("000000" + color).slice(-6); // pad with leading zeros
    color = "#" + color;                  // prepend #
    return color;
}
 //converts rgb to hex (source: http://jsfiddle.net/Mottie/xcqpF/1/light/)   
function rgb2hex(rgb){
 rgb = rgb.match(/^rgba?[\s+]?\([\s+]?(\d+)[\s+]?,[\s+]?(\d+)[\s+]?,[\s+]?(\d+)[\s+]?/i);
 return (rgb && rgb.length === 4) ? "#" +
  ("0" + parseInt(rgb[1],10).toString(16)).slice(-2) +
  ("0" + parseInt(rgb[2],10).toString(16)).slice(-2) +
  ("0" + parseInt(rgb[3],10).toString(16)).slice(-2) : '';
}    
    
    $("div").each(function(){
	var r = Math.round(Math.random() * 255);
	var g = Math.round(Math.random() * 255);
	var b = Math.round(Math.random() * 255);

	$(this).css("background-color", "rgb(" + r + "," + g + "," + b + ")");
        var bgColor = $(this).css('background-color');
        bgColor = rgb2hex(bgColor);
        var color =  invertColor(bgColor);  
        $(this).css("color", color);  
    });
    

});