There are several steps in the checkout process: contact_information, shipping_method, payment_method, processing and thank you page. All of these steps are all happening on one page. The checkout content added trough this dynamic behaviour can be a challenge to modify.
Things to be aware:
- All the checkout steps are on one checkout page: contact_information, shipping_method, payment_method, processing and thank you page.
- Big chunks of markup. Checkout.liquid introduce new Liquid variables like
content_for_order_summary. Those variables will return blocks of markup that can be hard to modify.
Page:changeare events triggered by Shopify. Page:load will fire when the content of each step is loaded, Page:change will fire when something is dynamically changing the DOM, like submitting a discount coupon.
Keep in mind that changes done on checkout require maintenance. With each checkout update verify that your code still works as intended.
Let's assume we want to add a popup on a payment gateway. It's a commune case where merchants want to give more information about a particular payment option. This is a quick boilerplate code I use when doing checkout modifications:
- Wrap your code in an IFFY, do not leak your variables.
- Detect the step using Shopify.Checkout.step, exit early.
- Use page:load and page:change events. Page:change is the key here, you do not want your event listeners and DOM to disappear after the user adds a discount code.
- Use data attributes not classes. We do not own that code but it's safer to assume that the data attributes added by Shopify are meant for this purpose.
- Keep it clean, use snippets.