Issue #3492855 by ivnish: Fix eslint warnings

Related to #3492855

js/imagick.colorpicker.js

-(function ($) {
-
-  "use strict";
-
+(function ($, Drupal) {
   // Adds the JS that binds the textarea with the farbtastic element.
-
   // Find each colorpicker placeholder:
   // initialize it,
   // then find the nearby textfield that is of type colorentry
   // and attach the colorpicker behavior to it.
   // This is so we can support more that one per page if necessary.
-
   Drupal.behaviors.colorpicker = {
-
-    attach: function (context) {
+    attach() {
       $('.colorpicker').each(function () {
-        var $this = $(this);
-        var linked_target = $('.colorentry', $this.closest('.colorform'));
-        $.farbtastic($this, linked_target);
+        const linkedTarget = $('.colorentry', $(this).closest('.colorform'));
+        $.farbtastic($(this), linkedTarget);
       });
-    }
-
+    },
   };
-
-})(jQuery);
+})(jQuery, Drupal);