Element.prototype.matchesSelector shim

matchesSelector_shim.js

var _hasOwnProperty = Object.prototype.hasOwnProperty;

if(!Element.prototype.matchesSelector) {
  Element.prototype.matchesSelector =
    Element.prototype.matches ||
    Element.prototype.webkitMatchesSelector ||
    Element.prototype.mozMatchesSelector ||
    Element.prototype.msMatchesSelector ||
    Element.prototype.oMatchesSelector || function(selector) {
      if(!selector)return false;
      if(selector === "*")return true;
      if(this === document.documentElement && selector === ":root")return true;
      if(this === document.body && selector === "body")return true;

      var thisObj = this,
        parent,
        i,
        str,
        tmp,
        match = false;

      if(/^[\w#\.][\w-]*$/.test(selector) || /^(\.[\w-]*)+$/.test(selector)) {
        switch (selector.charAt(0)) {
          case '#':
            return thisObj.id === selector.slice(1);
          break;
          case '.':
            match = true;
            i = -1;
            tmp = selector.slice(1).split(".");
            str = " " + thisObj.className + " ";
            while(tmp[++i] && match) {
              match = !!~str.indexOf(" " + tmp[i] + " ");
            }
            return match;
          break;
          default:
            return thisObj.tagName && thisObj.tagName.toUpperCase() === selector.toUpperCase();
        }
      }
      parent = thisObj.parentNode;
      
      if(parent && parent.querySelector) {
        match = parent.querySelector(selector) === thisObj;
      }

      if(!match && (parent = thisObj.ownerDocument)) {
        tmp = parent.querySelectorAll(selector);
          for (i in tmp ) if(_hasOwnProperty(tmp, i)) {
              match = tmp[i] === thisObj;
              if(match)return true;
          }
      }
        return match;
    }
}

if(!Element.prototype.matches)Element.prototype.matches = Element.prototype.matchesSelector;

_hasOwnProperty ??

I'd use something like this instead:

(function(){
  if (!Element.prototype.matches) {
    var matches2 = function(selector) {
      return (this.matchesSelector || this.msMatchesSelector || this.mozMatchesSelector || this.webkitMatchesSelector || this.oMatchesSelector).call(this, selector);
    };

    Element.prototype.matches = matches2;
  }
})();