Milestone

     fetch('prod-widgets.returning.ai/milestone-widget/NjYzGE5ZTQxM5Mzg2N2VmMWM3MDlhNi82OGFkMTYyYTAzOTM4NjdlZjFjNzA5YTY=/signin', 
     {
        method: 'POST', 
        headers: {
          'returningai-api-key': 'df09a52de262f1f802950815864',
          'email': '{email}',
          'Content-Type': 'application/json',
        }
      }).then((res) => {        
        res.json().then(data => {
          localStorage.setItem('returning-ai-widget-token', data.token)
        })
      }).catch((err) => {
        console.log(err)
      })

 <script>
    window.addEventListener('message', (event) => {
      if (event.origin === 'https://prod-widgets.returning.ai') { // Check origin for security
        const { type } = event.data;
        if (type === 'RETURNINGAI_WIDGET_TOKEN') {
            const value = localStorage.getItem('returning-ai-widget-token');
            // Send the value back to the parent window
            event.source.postMessage({ type: 'RETURNINGAI_WIDGET_TOKEN', value 
            }, event.origin);
        }
      }
    });
</script>

<iframe src="prod-widgets.returning.ai/milestone-widget/NjYzGE5ZTQxM5Mzg2N2VmMWM3MDlhNi82OGFkMTYyYTAzOTM4NjdlZjFjNzA5YTY" allow="clipboard-write" id="returningAiWidgetIframe" frameborder="0" width="100%" height="100%"></iframe>