Efficient wrapper for document.querySelectorAll

queryAll.js

// Always return an array of DOM elements
function queryAll(selector) {
  var id_sel = selector.match(/^#([\w-]*)$/),
      class_sel = !id_sel && selector.match(/^\.([\w-]+)$/),
      tag_sel = !class_sel && selector.match(/^[\w-]+$/);

  if (id_sel) {
    var elem = document.getElementById(id_sel[1]);
    return (elem ? [elem] : []);  // Always return an array
  }
  if (class_sel) {
    var elems = document.getElementsByClassName(class_sel[1]);
    return toArray(elems);
  }
  if (tag_sel) {
    var elems = document.getElementsByTagName(selector);
    return toArray(elems);
  }
  return toArray(document.querySelectorAll(selector));
  
  // Convert array-like collections to arrays (hoisted)
  function toArray(coll, from_index) {
    return Array.prototype.slice.call(coll, from_index);
  }
}