poppinlp/grunt-htmlhint-plus

module.exports = {
    id: 'foobar-exists',
    description: 'Checks that the data-foobar attribute exists on the html element',
    init: function (parser, reporter) {
        var self = this;
        parser.addListener('tagstart', function (event) {
            var tagName = event.tagName.toLowerCase(),
                mapAttrs = parser.getMapAttrs(event.attrs),
                col = event.col + tagName.length + 1;
            if (tagName === 'html' && !('data-foobar' in mapAttrs)) {
                reporter.warn('data-foobar of html tag must be present.', event.line, col, self, event.raw);
            }
        });
    }
};