diff --git a/client/src/entrypoints/admin/core.js b/client/src/entrypoints/admin/core.js
index a39e504a3d..cb633b598d 100644
--- a/client/src/entrypoints/admin/core.js
+++ b/client/src/entrypoints/admin/core.js
@@ -1,6 +1,7 @@
 import $ from 'jquery';
 import { escapeHtml } from '../../utils/text';
 import { initButtonSelects } from '../../includes/initButtonSelects';
+import { initTagField } from '../../includes/initTagField';
 import { initTooltips } from '../../includes/initTooltips';
 
 /* generic function for adding a message to message area through JS alone */
@@ -19,24 +20,6 @@ window.addMessage = addMessage;
 
 window.escapeHtml = escapeHtml;
 
-function initTagField(id, autocompleteUrl, options) {
-  const finalOptions = {
-    autocomplete: { source: autocompleteUrl },
-    preprocessTag(val) {
-      // Double quote a tag if it contains a space
-      // and if it isn't already quoted.
-      if (val && val[0] !== '"' && val.indexOf(' ') > -1) {
-        return '"' + val + '"';
-      }
-
-      return val;
-    },
-    ...options,
-  };
-
-  $('#' + id).tagit(finalOptions);
-}
-
 window.initTagField = initTagField;
 
 /*
diff --git a/client/src/includes/initTagField.test.js b/client/src/includes/initTagField.test.js
new file mode 100644
index 0000000000..72077e8d97
--- /dev/null
+++ b/client/src/includes/initTagField.test.js
@@ -0,0 +1,62 @@
+import $ from 'jquery';
+
+window.$ = $;
+
+import { initTagField } from './initTagField';
+
+describe('initTagField', () => {
+  let element;
+
+  const tagitMock = jest.fn(function tagitMockInner() {
+    element = this;
+  });
+
+  window.$.fn.tagit = tagitMock;
+
+  beforeEach(() => {
+    element = null;
+    jest.clearAllMocks();
+  });
+
+  it('should not call jQuery tagit if the element is not found', () => {
+    expect(tagitMock).not.toHaveBeenCalled();
+
+    initTagField('not-present');
+
+    expect(tagitMock).not.toHaveBeenCalled();
+  });
+
+  it('should call jQuery tagit if the element is found', () => {
+    expect(tagitMock).not.toHaveBeenCalled();
+
+    document.body.innerHTML = `
+    <main>
+      <input id="tag-input" type="text" value="abc" />
+    </main>
+    `;
+
+    initTagField('tag-input', '/path/to/autocomplete/', {
+      someOther: 'option',
+    });
+
+    // check the jQuery instance is the correct element
+    expect(element).toContain(document.getElementById('tag-input'));
+
+    // check the tagit util was called correctly with supplied params
+    expect(tagitMock).toHaveBeenCalledWith(
+      expect.objectContaining({
+        autocomplete: { source: '/path/to/autocomplete/' },
+        someOther: 'option',
+      }),
+    );
+
+    // check the supplied preprocessTag function
+    const [{ preprocessTag }] = tagitMock.mock.calls[0];
+
+    expect(preprocessTag).toBeInstanceOf(Function);
+
+    expect(preprocessTag()).toEqual();
+    expect(preprocessTag('"flat white"')).toEqual(`"flat white"`);
+    expect(preprocessTag("'long black'")).toEqual(`"'long black'"`);
+  });
+});
diff --git a/client/src/includes/initTagField.ts b/client/src/includes/initTagField.ts
new file mode 100644
index 0000000000..c714b42432
--- /dev/null
+++ b/client/src/includes/initTagField.ts
@@ -0,0 +1,42 @@
+import $ from 'jquery';
+
+declare global {
+  interface JQuery {
+    tagit(...args): void;
+  }
+}
+
+/**
+ * Initialises the tag fields using the jQuery tagit widget
+ *
+ * @param id - element id to initialise against
+ * @param source -  auto complete URL source
+ * @param options - Other options passed to jQuery tagit
+ */
+const initTagField = (
+  id: string,
+  source: string,
+  options: Record<string, any>,
+): void => {
+  const tagFieldElement = document.getElementById(id);
+
+  if (!tagFieldElement) return;
+
+  const finalOptions = {
+    autocomplete: { source },
+    preprocessTag(val: any) {
+      // Double quote a tag if it contains a space
+      // and if it isn't already quoted.
+      if (val && val[0] !== '"' && val.indexOf(' ') > -1) {
+        return '"' + val + '"';
+      }
+
+      return val;
+    },
+    ...options,
+  };
+
+  $('#' + id).tagit(finalOptions);
+};
+
+export { initTagField };