how to add custom script in shopify without using script tag

Question

like HT Script application( https://apps.shopify.com/ht-script )。you can add custom script like

"var a=1";

and we can see custom script in html header like

<script>var a=1;</script>

i know Shopify API support script tag to add custom script like

<script src="http://xxxx.js"></script>

so,what's the principle behind HT Sciprt application，why it don't need src 。

Answer 1

App has following permissions:

That means it uses following access scopes

• read_themes
• write_themes

Way how it probably works

1. Reads list of themes

   GET /admin/api/2021-01/themes.json

2. With that list it can find active theme.

   Field "role" equals "main".

3. With active theme id it can access assets.

   GET /admin/api/2021-01/themes/{theme_id}/assets.json?asset[key]=layout/theme.liquid

4. With content of that file you can modify headers as you want with html parser.

5. Update the same file with another api call

   PUT /admin/api/2021-01/themes/{theme_id}/assets.json

Of course you can create some cron job in your application to make sure that your modified scripts are always up to date with template.

Helpful links:

• Access scopes in Shopify Rest API
• Shopify theme Rest API reference
• Shopify asset Rest API reference