Detect HTML strings (extracted from jQuery's core)

isHTMLString.js

// https://github.com/jquery/jquery/blob/master/src/core/init.js#L14
var isHTMLString = (function() {
  var rHTML = /^(?:\s*(<[\w\W]+>)[^>]*|#([\w-]*))$/;
  return function(str) {
    return rHTML.test(str);
  };
}());