This function allows a developer to set attributes on an HTML element using selector-esque syntax, and return a selector-syntax of the current jQuery object. This is by no means production ready/complete. Hopefully someone finds this as useful as I do.

jQuery.selectors.js

/*
   Copyright 2014 Paul Bjorkstrand

   Licensed under the Apache License, Version 2.0 (the "License");
   you may not use this file except in compliance with the License.
   You may obtain a copy of the License at

     http://www.apache.org/licenses/LICENSE-2.0

   Unless required by applicable law or agreed to in writing, software
   distributed under the License is distributed on an "AS IS" BASIS,
   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   See the License for the specific language governing permissions and
   limitations under the License.
 */

/*
 * Syntax:
 * var a = $("<div/>").selectors("#id.class1.class2[attr1=val1]"); // div with id "id", classes "class1" & "class2", and attribute "attr1" with value "val1"
 * a.selectors() // prints div#id.class1.class2[attr1=val1]
 */

(function($, console) {
  "use strict";
  var REGEX = /(^#|\$|\.|:)[^.[{:$]+|(\[|\{)[^\]}]+(\]|\})/g;
  
  $.fn.selectors = $.fn.$ = function(arg) {
    if (typeof arg === "string") {
      return set(this, arg);
    } if (typeof arg === "boolean" || $.isArray(arg)) {
      return get(this, arg)
    } else {
      return get(this);
    }
  };
  
  function set(obj, selectorString) {
    var match, matchStr, index, name, val;
    selectorString = selectorString.trim();
    
    if (/\s/.test(selectorString)) {
      throw "jQuery selectors plugin: The selector string must not contain any whitespace";
    }
    
    while ((match = REGEX.exec(selectorString)) && (matchStr = match[0])) {
      switch(matchStr[0]) {
        case "#":
          if (matchStr[1] !== "!") {
            obj.attr("id", matchStr.slice(1));
          } else {
            obj.removeAttr("id");
          }
          break;
        case ".":
          if (matchStr[1] !== "!") {
            obj.addClass(matchStr.slice(1));
          } else {
            obj.removeClass(matchStr.slice(2));
          }
          break;
        case "[":
          if (matchStr[matchStr.length-1] === "]") {
            if (matchStr[1] !== "!") {
              index = matchStr.indexOf("=");
              if (index !== -1) {
                name = matchStr.slice(1,index);
                val = matchStr.slice(index + 1, -1);
                obj.attr(name, val);
              } else {
                name = matchStr.slice(1,-1);
                obj.attr(name,"");
              }
            } else {
              name = matchStr.slice(2,-1);
              obj.removeAttr(name);
            }
          } else {
            console.error("Missing end bracket in " + matchStr);
          }
          break;
        case "{":
          // future set properties
          console.warn("{a=b} expressions not implemented");
          continue;
          index = matchStr.indexOf("=");
          if (matchStr[matchStr.length-1] === "}") {
            if (index !== -1) {
              name = matchStr.slice(1,index);
              val = matchStr.slice(index + 1, -1);
            } else {
              console.error("Property setting requires a name and value. Example: {disabled=b@true}")
            }
          } else {
            console.error("Missing end brace in " + matchStr);
          }
          break;
        case ":":
          // future: special selectors using : and :!
          console.warn(": expressions not implemented");
        case "$":
          // future: call a jquery object function with the given parameters (i.e. .val(newVal))
          console.warn("$ expressions not implemented");
        default:
          // how did we get here
          console.warn("Selector not found: " + matchStr); 
      }
    }
    
    return obj;
  }
  
  function get(obj, includeAttributes) {
    return obj.map(function(index, element) {
      var id = $(element).attr("id"),
          classes = $(element).attr("class"),
          attributes = [];
          
      if (id) {
        id = "#" + id;
      } else {
        id = "";
      }
      
      if (classes) {
        classes = "." + classes.split(/\s+/).join(".");
      } else {
        classes = "";
      }
      
      if (includeAttributes !== false) {
        $.each(element.attributes, function(key, attr) {
          if (!$.isArray(includeAttributes) || $.inArray(key, includeAttributes)) {
            if (attr.name !== "class" && attr.name !== "id") {
              if (attr.value) {
                attributes.push("["+attr.name+"="+attr.value+"]");
              } else {
                attributes.push("["+attr.name+"]");
              }
            }
          }
        });
      }
      
      attributes = attributes.join("");
      return element.tagName.toLowerCase() + id + classes + attributes;
    });
  }
})(jQuery, window.console);