jQuery run code if element exists

jquery.exists.js

/**
 * Tiny jQuery Plugin
 * by Chris Goodchild
 * https://css-tricks.com/snippets/jquery/check-if-element-exists/
 *
 */
$.fn.exists = function(callback) {
  if (this.length) {
    var args = [].slice.call(arguments, 1);
    callback.call(this, args);
  }
  return this;
};

// Usage
$('div.test').exists(function() {
  this.append('<p>I exist!</p>');
});