fix #2731: put file loader strings in metafile

Author: evanw

CHANGELOG.md

@@ -1,5 +1,31 @@
 # Changelog
 
+## Unreleased
+
+* Include `file` loader strings in metafile imports ([#2731](https://github.com/evanw/esbuild/issues/2731))
+
+    Bundling a file with the `file` loader copies that file to the output directory and imports a module with the path to the copied file in the `default` export. Previously when bundling with the `file` loader, there was no reference in the metafile from the JavaScript file containing the path string to the copied file. With this release, there will now be a reference in the metafile in the `imports` array with the kind `file-loader`:
+
+    ```diff
+     {
+       ...
+       "outputs": {
+         "out/image-55CCFTCE.svg": {
+           ...
+         },
+         "out/entry.js": {
+           "imports": [
+    +        {
+    +          "path": "out/image-55CCFTCE.svg",
+    +          "kind": "file-loader"
+    +        }
+           ],
+           ...
+         }
+       }
+     }
+    ```
+
 ## 0.16.6
 
 * Do not mark subpath imports as external with `--packages=external` ([#2741](https://github.com/evanw/esbuild/issues/2741))

internal/bundler/linker.go

@@ -4223,6 +4223,11 @@ func (c *linkerContext) generateCodeForFileInChunkJS(
 		sourceIndex: partRange.sourceIndex,
 	}
 
+	if file.InputFile.Loader == config.LoaderFile {
+		result.JSONMetadataImports = append(result.JSONMetadataImports, fmt.Sprintf("\n        {\n          \"path\": %s,\n          \"kind\": \"file-loader\"\n        }",
+			helpers.QuoteForJSON(file.InputFile.UniqueKeyForAdditionalFile, c.options.ASCIIOnly)))
+	}
+
 	waitGroup.Done()
 }
 

internal/bundler/snapshots/snapshots_loader.txt

@@ -1296,6 +1296,10 @@ d {
           "kind": "import-statement",
           "external": true
         },
+        {
+          "path": "out/file-NVISQQTV.file",
+          "kind": "file-loader"
+        },
         {
           "path": "out/copy-O3Y5SCJE.copy",
           "kind": "import-statement"

lib/shared/types.ts

@@ -453,7 +453,7 @@ export interface Metafile {
       }
       imports: {
         path: string
-        kind: ImportKind
+        kind: ImportKind | 'file-loader'
         external?: boolean
       }[]
       exports: string[]