This tip comes by way of a conversation in the Shopify Partner Slack between Edi and Lewis.

The question is, how do you access variables that are defined "below" your current scope, such as when a section defines a variable that you want to access in the section that included the snippet

Option 1 - Capture

Option 1 is to output the value from the snippet, and capture it in the section.

Example:

snippets/unique.liquid

﹛﹛ 'now' | date: '%N' ﹜﹜

sections/section-name.liquid

﹛% capture id %﹜
﹛% render 'unique' %﹜
﹛% endcapture %﹜
<div id="Section--﹛﹛id ﹜﹜"></div>

Option 2 - javascript

Option 2 is to use javascript to create a global variable in the snippet and then reference that same variable later in the section via js

Example:

snippet.liquid

﹛%- assign item_count = 0 -%﹜
﹛% for item in loop %﹜
﹛%- assign item_count = item_count | plus: 1 -%﹜

﹛% endfor %﹜

section.liquid

﹛% render 'unique' %﹜
<script>
const item_count = window.js_item_count
if (item_count === undefined || 0 ) {
...
} else {
...
}
</script>