Send a dynamic date from product page to checkout

I have a script that generates and displays a dynamic date on a product page.

How do I send this completion date through to the checkout page with the other variables when the buy now button is pressed?

Thanks in advance

##### Completion Estimate
  

      
  

Shopify-scripts and it’s subtype Line-item-scripts are for custom ruby language scripts which operated in the checkout process and have nothing to do with frontend javascript.

To pass info from a theme on the online sales channel through to checkout and the order use either line item properties or cart attributes .

https://community.shopify.com/topic/616503

https://community.shopify.com/topic/613718

Thanks. I can send other variant info to the shopping basket,but I can’t send a dynamic date. is this possible?