Pre-populate Calendly fields

I’m embedding Calendly into Webflow, and everything is working. However, I want to pre-populate the Calendly form, which is not working. Any ideas what’s going on? Here’s the code I’m using:

const params = (new  URL(window.location)).searchParams

Calendly.initInlineWidget({
    url: 'https://calendly.com/mylink/30min',
    prefill: {
        name: params.get('john'),
        email: params.get('john@gmail.com')
    }         
});