gistfile1.js

$(document).ready(function() {

    function splitArrayInGroupsOf(jquery_object_array, group_size) {
        var counter = 1,
            group = [],
            groups = [];

        jquery_object_array.each(function() {
            group.push($(this)[0]);
            if (counter % group_size === 0) {
                groups.push(group);
                group = [];
            }
            counter++;
        });
        return groups;
    }

    function sameHeightFor(jquery_object_array) {
        var jquery_objects_heights = [],
            highest_jquery_object;

        $(jquery_object_array).each(function() {
            jquery_objects_heights.push($(this).height());
        });
        highest_jquery_object = Math.max.apply(null, jquery_objects_heights);
        $(jquery_object_array).height(highest_jquery_object);
    }

    function sameHeightForColumnRowElements(selected_elements, column_number) {
        // Reset elements to original height.
        selected_elements.css('height', '');

        if (column_number !== 1 ) {
            var col_groups = splitArrayInGroupsOf(selected_elements, column_number);

            for (var i = 0; i < col_groups.length; i++) {
                sameHeightFor(col_groups[i]);
            }
        }
    }

    function getColumnNumber(viewport_width) {
        var columns;
        if (viewport_width > 960) {
            columns = 3;
        }
        else if (viewport_width <= 960 && viewport_width >= 640 ) {
            columns = 2;
        }
        else {
            columns = 1;
        }
        return columns;
    }

    var viewport_width = $(window).width(),
        column_number = getColumnNumber(viewport_width),
        column_elements = $('.js-column-row-element');

    // Init
    sameHeightForColumnRowElements(column_elements, column_number);

    // Control on Window Resize
    $(window).resize(function() {
        var new_column_number = getColumnNumber($(window).width());

        if (new_column_number !== column_number) {
            column_number = new_column_number;
            sameHeightForColumnRowElements(column_elements, column_number);
        }
    });

});