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[FIX] TypeError: $(...).once is not a function

Getting TypeError: $(...).once is not a function in your Drupal 8 site? Easily fixed.

Pridal/a lubo dňa Po, 11/02/2020 - 07:39
Check for the code

And look for 2x defined jquery in your code.

Edit your bootstrap.libraries.yml file

Unless specified, your theme does not use jquery.once as dependency. This can result in and error TypeError: $(...).once is not a function when using BigPipe, where you just need .once() function as salt.

Add the following lines in your bootstrap.libraries.yml file
  dependencies:
    - core/jquery
    - core/jquery.once

So the whole file can be somehow like:

framework:
  css:
    theme:
      css/select2.min.css: {}
      css/style.css: {}
  js:
    js/select2.full.min.js: {}
    js/scripts.js: {}
  dependencies:
    - core/jquery
    - core/jquery.once

Remember, YAML files are space-sensitive!

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