Angular 2+项目中部分免费Font Awesome图标无法加载求助

Hey there! Let's break down why your fa-sync icon isn't rendering, even though it's marked as free on the Font Awesome site.

The Core Issue: Version Mismatch #

You're using Font Awesome 4.7.0 (as confirmed in your package files), but the fa-sync icon didn't exist until Font Awesome 5. The 4.x version of Font Awesome uses a completely different set of icon classes, and fa-sync simply isn't part of that library.

Quick Fix: Use the 4.x Equivalent #

If you don't want to upgrade right now, 4.7.0 has a direct alternative that looks identical to what you'd expect from fa-sync: fa-refresh. Just swap your code with:
<i class="fa fa-refresh"></i>

Long-Term Solution: Upgrade to Font Awesome 5+ #

If you really want to use fa-sync (and unlock the full suite of newer free icons), upgrading is the way to go. Here's how to do it properly in Angular:

1. Uninstall the old package
   Run this command in your project folder:

   npm uninstall font-awesome
   

2. Install the official Angular Font Awesome packages
   These are optimized for Angular and support tree-shaking (so you only load the icons you actually use):

   npm install @fortawesome/angular-fontawesome @fortawesome/fontawesome-svg-core @fortawesome/free-solid-svg-icons
   

3. Set up the module
   Open app.module.ts and add these imports:

   import { FontAwesomeModule } from '@fortawesome/angular-fontawesome';
   import { library } from '@fortawesome/fontawesome-svg-core';
   import { faSync } from '@fortawesome/free-solid-svg-icons';
   
   // Add the sync icon to the library for global use
   library.add(faSync);
   
   @NgModule({
     imports: [
       // ... your other imports
       FontAwesomeModule
     ]
   })
   export class AppModule { }
   

4. Use the icon in your template
   Replace the old <i> tag with the Angular component:

   <fa-icon [icon]="['fas', 'sync']"></fa-icon>
   

Alternative: Stick to the Old <i> Tag Syntax #

If you prefer keeping the familiar <i> tag approach, install the standalone CSS package instead:

npm install @fortawesome/fontawesome-free

Then update your angular.json styles array to include:

"styles": [
  "src/styles.css",
  "node_modules/bootstrap/dist/css/bootstrap.min.css",
  "node_modules/@fortawesome/fontawesome-free/css/all.css"
]

Now you can use the new icon classes like <i class="fas fa-sync"></i> (note the fas prefix for solid icons—4.x didn't use these prefixes, which is another key difference between versions!).

Quick Angular & Font Awesome Best Practice #

The official @fortawesome/angular-fontawesome package is the recommended approach for Angular projects. It integrates smoothly with Angular's change detection, uses sharper SVG icons, and reduces your app's bundle size by only including the icons you reference.

内容的提问来源于stack exchange，提问作者mark_h