Just thought I’d post how I got these working with html after reading closely through the thread. (I would say in future to let everyone know in the original thread about the new system settings to get icons going on headers etc).
To add some icons go to /admin/site_settings/category/all_results?filter=icons and add the prefixes accordingly. “Add additional FontAwesome 5 icons that you would like to include in your assets. Use prefix ‘fa-’ for solid icons, ‘far-’ for regular icons and ‘fab-’ for brand icons.”
Eg fa-newspaper.
Then reference them in your html. Eg <svg class="fa d-icon d-icon-newspaper svg-icon svg-node" aria-hidden="true"><use xlink:href="#newspaper"></use></svg>.
We’ve also fully converted to SVG icons instead of relying on a font icon. This is more efficient than shipping a giant and mostly unused icon font. Plus, it’s now much easier to switch any visible icon in Discourse with something else, even a completely custom one-off glyph that you created.
That specific icon has been removed from the list of free font awesome icons. The closest equivalent is long-arrow-alt-left. If you are limited to using HTML, you would use:
Thanks @tshenry
You are so awesome
I tried to use long-arrow-alt-left, it worked well.
But can you tell me more if I still want to use long-arrow-left.
Unfortunately, as I mentioned above, that icon is not available in the free tier of Font Awesome icons. If long-arrow-alt-left will not work for you, I think your best option might be to create your own version and use a plugin as described in the post above.