How to insert discount code into URL so discount is auto-applied to all prices

Store Design
34

I have been searching around today to work out how to do this easily, without apps, and came up with just a few lines of JS that will do it. I’ve shared the JS here: https://henryreith.co/automatically-add-discount-codes-to-shopify-checkout/. Hope this help’s other people looking for a solution too.