Simple DOM Selector for Vanilla JS

__.js

var __;

__ = function(selector, filter) {
  'use strict';

  var response;

  function filtering(selectors, filter) {
    switch (filter) {
      case "first":
        return selectors[0];
        break;
      case "last":
        return selectors[selectors.length - 1];
        break;
      default:
        return selectors[filter];
        break;
    }
  }

  response = [];

  selector = selector.trim();
  if (typeof filter === "string") {
    filter = filter.trim();
  }

  if (/^[.#a-zA-Z0-9_-][a-zA-Z_-]+$/.test(selector)) {
    switch (selector.substr(0, 1)) {
      case '.':
        response = document.getElementsByClassName(selector.substr(1));
        break;
      case '#':
        response.push(document.getElementById(selector.substr(1)));
        break;
      default:
        response = document.getElementsByTagName(selector);
        break;
    }
    if (typeof filter !== "undefined") {
      response = filtering(response, filter)
    }
  } else {
    if (typeof filter !== "undefined") {
      switch (filter) {
        case "first":
          response = document.querySelector(selector);
          break;
        case "last":
          response = document.querySelectorAll(selector);
          response = response[response.length - 1];
          break;
        default:
          response = document.querySelectorAll(selector);
          response = response[filter];
          break;
      }
    } else {
      response = document.querySelectorAll(selector);
      if (response.length < 1) {
        response = [];
      }
    }
  }

  return response;
};

The filter parameter accepts first, last or the number of the element it you'll want to get.