CODE EXAMPLE FOR JAVASCRIPT

document get all elements by property has white color

//This function will return an array of rgb/rgba colors declared via inline styles or CSS classes

function getAllColors() {
    // regex via http://stackoverflow.com/a/7543829/149636
    var rgbRegex = /^rgba?((d+),s*(d+),s*(d+)(?:,s*(d+(?:.d+)?))?)$/;

    var allColors = [];

    var elems = document.getElementsByTagName('*');
    var total = elems.length;

    var x,y,elemStyles,styleName,styleValue,rgbVal;

    for(x = 0; x < total; x++) {
        elemStyles = window.getComputedStyle(elems[x]);

        for(y = 0; y < elemStyles.length; y++) {
            styleName = elemStyles[y];
            styleValue = elemStyles[styleName];

            if(!styleValue) {
                continue;
            }

            // convert to string to avoid match exceptions
            styleValue += "";

            rgbVal = styleValue.match(rgbRegex);
            if(!rgbVal) { // property does not contain a color
                continue;
            }

            if(allColors.indexOf(rgbVal.input) == -1) { // avoid duplicate entries
                allColors.push(rgbVal.input);
            }

        }

    }

    return allColors;
}