Mate / Suggest

        var evalSuggest = function(selector) {
            selector = selector || '*';
            var self = this;
            this.getClasses = function(selector, classHint) {
                classHint = classHint || '';
                var lastClassHint = classHint.substr(classHint.lastIndexOf('.') + 1);
                classHint = classHint.replace(/\.$/, '');
                var classHintRegex = new RegExp('^' + classHint.replace(/\./, ''));
                var res = {};
                var els = document.querySelectorAll(selector + classHint);
                if (els.length == 0) {
                    els = document.querySelectorAll(selector);
                }
                var classNames = [];
                for (var i in els) {
                    classNames = els[i].className;
                    if (!classNames) {
                        continue;
                    }
                    classNames = classNames.split(' ');
                    for (var i in classNames) {
                        if (classHintRegex.test(classNames[i])) {
                            res[classNames[i]] = true;
                        }
                        if (lastClassHint == '') {
                            res[classNames[i]] = true;
                        }
                    }
                }
                return res;
            };
            this.getIds = function(selector, idHint) {
                idHint = idHint || '';
                var idHintRegex = new RegExp('^' + idHint);
                var res = {};
                var els = document.querySelectorAll(selector);
                var id = null;
                for (var i in els) {
                    id = els[i].id || null;
                    if (!id) {
                        continue;
                    }
                    if (idHintRegex.test(id)) {
                        res[id] = true;
                    }
                }
                return res;
            };
            this.getInnerTags = function(selector) {
                var res = {};
                if (selector.charAt(selector.length - 1) == '>') {
                    selector += '*';
                }
                var innerTagName = selector.substr(selector.lastIndexOf('>') + 1);
                var innerTagNameRegex = tagName == '*' ? null : new RegExp('^' + innerTagName, 'i');
                els = document.querySelectorAll(selector);
                if (els.length == 0) {
                    selector = selector.substr(0, selector.lastIndexOf('>')) + '>*';
                    els = document.querySelectorAll(selector);
                }
                for (var i in els) {
                    if (!els[i].tagName) {
                        continue;
                    }
                    if (innerTagName == '*') {
                        res[els[i].tagName] = true;
                        continue;
                    }
                    if (innerTagNameRegex.test(els[i].tagName)) {
                        res[els[i].tagName] = true;
                    }
                }
                return res;
            };
            this.getLastType = function(obj) {
                var key = '';
                var highest = -1;
                for (var i in obj) {
                    if (obj[i] > highest) {
                        highest = obj[i];
                        key = i;
                    }
                }
                return key;
            };
            var res = {};
            var lastTypePositions = {
                dot: selector.lastIndexOf('.'),
                hash: selector.lastIndexOf('#'),
                arrow: selector.lastIndexOf('>')
            }
            var lastType = getLastType(lastTypePositions);
            var lookingFor = 'tag';
            if (lastType == 'dot') {
                lookingFor = 'class';
            }
            if (lastType == 'hash') {
                lookingFor = 'id';
            }
            if (lastType == 'arrow') {
                lookingFor = 'innerTag';
            }
            var selector = selector.replace(/( )*>\1*/g, '>').split(' ');
            var selectorString = '';
            var els = null;
            for (var i in selector) {
                if (i < selector.length - 1) {
                    selectorString += selector[i] + ' ';
                    continue;
                }
                var tagName = selector[i].match(/^[a-z0-9>*]+/i);
                tagName = !tagName ? '*' : tagName[0];
                var tagNameRegex = tagName == '*' ? null : new RegExp('^' + tagName, 'i');
                var classString = selector[i].match(/\.[a-z0-9\-_.]+/i);
                classString = !classString ? '' : classString[0];
                var id = selector[i].match(/#[a-z0-9\-_]+/i);
                id = !id ? '' : id[0];
                if (lookingFor == 'tag') {
                    els = document.querySelectorAll(selectorString + tagName);
                    if (els.length == 0) {
                        els = document.querySelectorAll('*');
                    }
                    var tmp = {};
                    for (var i in els) {
                        if (!els[i].tagName) {
                            continue;
                        }
                        tmp[els[i].tagName] = true;
                    }
                    if (Object.keys(tmp).length == 1) {
                        els = document.querySelectorAll('*');
                    }
                    for (var i in els) {
                        if (!els[i].tagName) {
                            continue;
                        }
                        if (tagName == '*') {
                            res[els[i].tagName] = true;
                            continue;
                        }
                        if (tagNameRegex.test(els[i].tagName)) {
                            res[els[i].tagName] = true;
                        }
                    }
                }
                if (lookingFor == 'class') {
                    var classes = self.getClasses(tagName, classString);
                    res = classes;
                }
                if (lookingFor == 'id') {
                    var id = selector[selector.length - 1].split('#')[1];
                    var ids = self.getIds(tagName, id);
                    res = ids;
                }
                if (lookingFor == 'innerTag') {
                    var tags = self.getInnerTags(tagName);
                    res = tags;
                }
            }
            var resArr = [];
            for(var i in res) {
                resArr.push(i);
            }
            return resArr;
        }