In my develop process, I meet a scenario: I only want to load a JavaScript file when a page has an element whose class is test, so what can I do? How to know a page whether has this element?

  • Instead of testing for pages with a class of test, why not attach the js file in the same place as the logic where the test class is being added? Commented Jan 25, 2021 at 2:29
  • 1
    Because the test calss is added in ckeditor, and we have many sites has the same class.
    – MyMercury
    Commented Jan 25, 2021 at 3:48

1 Answer 1


Well one way would be to just add the script always and check for the existence of test class there.

(function ($, Drupal) {
    Drupal.behaviors.tester = {

        attach: function (context) {
           if (context.querySelector('.test')) {
               // Do something
               // Or maybe load another JS file dynamically

})(jQuery, Drupal);

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