• I have been trying to get Google ReCAPTCHA v2 invisible work with sveltekit 2 / svelte 5 and I have run into a few issues
• First of all this is the documentation for how to load CAPTCHA in your javascript code
• And here is a section on how to actually go about using it to display an INVISIBLE v2 CAPTCHA
• I have tried all the LLMs (Claude, ChatGPT, Gemini, Deepseek, Grok) and got only half baked answers from all of them before asking this question
• I have 4 forms, a login, signup, fot and reset form and I want to use the same ReCAPTCHA everywhere.
• So I created a component that needs to have 2 functions as follows

GoogleReCAPTCHA.svelte

async function init() {
...
}

export async function getToken() {
  try {
    await init()
    ...
   }
   catch (e) {
   ...
   }
}

## Problem 1

• Let us talk about the second function first
• ReCAPTCHA wants you to add 3 callback functions to your window object

<script lang="ts">
...
function onDataCallback(token: string) {
  console.log('I got the token here but how do I send it to the calling component', token)
}

function onErrorCallback() {
  console.log('something went wrong with ReCAPTCHA')
} 

function onExpiredCallback() {
  console.log('your ReCAPTCHA expired');
}

onMount(() => {
  window.onDataCallback = onDataCallback
  window.onErrorCallback = onErrorCallback
  window.onExpiredCallback = onExpiredCallback
})

...
</script>
<div class="g-recaptcha"
      data-sitekey="_your_site_key_"
      data-callback="onDataCallback"
      data-error-callback="onErrorCallback"
      data-expired-callback="onExpiredCallback"
      data-size="invisible">
</div>

• How do I promisify this to return a token to the caller?
• If the functions are not defined on window , they are simply not called
• If the functions are defined inside a function, they are again not called
• The snippet below doesn't work

<script lang="ts'>
export async function getToken() {
  return new Promise((resolve, reject) => {
     function onDataCallback(token: string) {
       resove(token)
     }
     function onErrorCallback() {
       reject(throw new Error('Something went wrong with RECAPTCHA'))
     }
     function onExpiredCallback() {
       reject(throw new Error('RECAPTCHA expired'))
     }
     window.onDataCallback = onDataCallback
     window.onErrorCallback = onErrorCallback
     window.onExpiredCallback = onExpiredCallback
  })
}
</script>
<div class="g-recaptcha"
      data-sitekey="_your_site_key_"
      data-callback="onDataCallback"
      data-error-callback="onErrorCallback"
      data-expired-callback="onExpiredCallback"
      data-size="invisible">
</div>

Problem 2

• How to promisify this so that the promise awaits till recaptha loads

Question

• Basically a single function like getToken() should be able to wait for recaptcha to load, return a promise with the token if succesful and an error if something went wrong. I can't seem to make this work using promises