1 files changed, 48 insertions, 0 deletions
diff --git a/app/assets/javascripts/captcha/init_recaptcha_script.js b/app/assets/javascripts/captcha/init_recaptcha_script.js
new file mode 100644
index 00000000000..b9df7604ed1
--- /dev/null
+++ b/app/assets/javascripts/captcha/init_recaptcha_script.js
@@ -0,0 +1,48 @@
+// NOTE: This module will be used in https://gitlab.com/gitlab-org/gitlab/-/merge_requests/52044
+import { memoize } from 'lodash';
+
+export const RECAPTCHA_API_URL_PREFIX = 'https://www.google.com/recaptcha/api.js';
+export const RECAPTCHA_ONLOAD_CALLBACK_NAME = 'recaptchaOnloadCallback';
+
+/**
+ * Adds the Google reCAPTCHA script tag to the head of the document, and
+ * returns a promise of the grecaptcha object
+ * (https://developers.google.com/recaptcha/docs/display#js_api).
+ *
+ * It is memoized, so there will only be one instance of the script tag ever
+ * added to the document.
+ *
+ * See the reCAPTCHA documentation for more details:
+ *
+ * https://developers.google.com/recaptcha/docs/display#explicit_render
+ *
+ */
+export const initRecaptchaScript = memoize(() => {
+  // Appends the the reCAPTCHA script tag to the head of document
+  const appendRecaptchaScript = () => {
+    const script = document.createElement('script');
+    script.src = `${RECAPTCHA_API_URL_PREFIX}?onload=${RECAPTCHA_ONLOAD_CALLBACK_NAME}&render=explicit`;
+    script.classList.add('js-recaptcha-script');
+    document.head.appendChild(script);
+  };
+
+  return new Promise((resolve) => {
+    // This global callback resolves the Promise and is passed by name to the reCAPTCHA script.
+    window[RECAPTCHA_ONLOAD_CALLBACK_NAME] = (val) => {
+      // Let's clean up after ourselves. This is also important for testing, because `window` is NOT cleared between tests.
+      // https://github.com/facebook/jest/issues/1224#issuecomment-444586798.
+      delete window[RECAPTCHA_ONLOAD_CALLBACK_NAME];
+      resolve(val);
+    };
+    appendRecaptchaScript();
+  });
+});
+
+/**
+ * Clears the cached memoization of the default manager.
+ *
+ * This is needed for determinism in tests.
+ */
+export const clearMemoizeCache = () => {
+  initRecaptchaScript.cache.clear();
+};