feat: add --import

CHANGELOG.md

@@ -4,6 +4,7 @@
 
 - **feat**: Shim `import.meta.{dirname,filename}`.
 - **refactor**: Use `"type": "module"` and change main file extension to `.js`.
+- **refactor**: Use `--import` instead of `--loader` when possible.
 
 ## 0.10.5
 

docs/guide/cli.md

@@ -17,7 +17,7 @@ $ esbuild-dev -p:./plugin.ts main.ts
 # build and run main.ts, with plugin from file ./plugin.ts
 # longhand: --plugin
 
-$ esbuild-dev --loader main.ts
+$ esbuild-dev --import main.ts
 # run main.ts with esm loader
 # in this mode, --cjs, --watch and --plugin are not supported.
 ```

src/args.ts

@@ -97,6 +97,7 @@ export const EsbuildFlags: readonly FlagConfig[] = [
 export const EsbuildDevFlags: readonly FlagConfig[] = [
   ["no-warnings", boolean],
   ["loader", boolean],
+  ["import", boolean],
   ["cjs", boolean],
   ["shims", boolean],
   ["watch", boolean, { alias: ["w"] }],
@@ -108,6 +109,7 @@ export const EsbuildDevFlags: readonly FlagConfig[] = [
 export interface EsbuildDevOptions {
   noWarnings?: boolean;
   loader?: boolean;
+  import?: boolean;
   cjs?: boolean;
   shims?: boolean;
   watch?: boolean;

src/commands/default.ts

@@ -26,6 +26,7 @@ export async function defaultCommand(entry: string, argsBeforeEntry: string[], a
 
   const devOptions = { shims: true, ...devOptionsRaw } as EsbuildDevOptions;
   const buildOptions = buildOptionsRaw as BuildOptions & { format: Format };
+  if (devOptions.import) devOptions.loader = true;
   if (devOptions.loader && (devOptions.cjs || devOptions.plugin || devOptions.watch || devOptions.include)) {
     throw new Error(`--cjs, --plugin, --watch and --include are not supported with --loader`);
   }
@@ -35,7 +36,11 @@ export async function defaultCommand(entry: string, argsBeforeEntry: string[], a
 
   let spawnArgs: string[];
   if (devOptions.loader) {
+    const v = process.versions.node.split(".").map(e => Number.parseInt(e));
+    const register = v[0] > 20 || (v[0] === 20 && v[1] >= 6) || (v[0] === 18 && v[1] >= 19);
+
     spawnArgs = ["--loader", loaderPath, "--enable-source-maps", entry, ...argsToEntry];
+    if (register) spawnArgs[0] = "--import";
     if (devOptions.node) spawnArgs.splice(3, 0, ...devOptions.node);
     if (devOptions.noWarnings) spawnArgs.unshift("--no-warnings");
 

src/help.txt

@@ -1,12 +1,12 @@
 
 Usage:
-  esbuild-dev [--loader] [--cjs] [--watch] [--plugin:name] main.ts ...
+  esbuild-dev [--import] [--cjs] [--watch] [--plugin:name] main.ts ...
   esbuild-dev external [--bare] main.ts ...
   esbuild-dev temp
 
 Options:
-  --loader              Use `--loader` to run the file, which is helpful
-                        when using other coverage tools.
+  --import              Use `--import` to run the file, which is helpful
+  --loader              when using other coverage tools.
                         In this mode, plugins are not supported.
 
   --no-warnings         Using experimental loader api will cause node
@@ -16,7 +16,7 @@ Options:
   --cjs                 Change the outfile format to CJS. For example,
                         `__dirname` can only be used in CJS, and
                         `import.meta` can only be accessed in ESM.
-                        This option cannot be used with `--loader`.
+                        This option cannot be used with `--import`.
 
   --shims               Replace `import.meta.url` and `__dirname` with absolute
                         path in .[tj]s files. This is enabled by default.

src/loader.ts

@@ -1,3 +1,4 @@
+import module from "module";
 import { Loader as EsbuildLoader, PartialMessage, formatMessages, transform } from "esbuild";
 import { readFile } from "fs/promises";
 import { dirname, extname } from "path";
@@ -140,3 +141,8 @@ export async function load(url: string, context: LoadContext, defaultLoad: Loade
 
   return defaultLoad(url, context, defaultLoad);
 }
+
+if (module.register) {
+  process.setSourceMapsEnabled(true);
+  module.register(`./loader.js?${Date.now()}`, import.meta.url);
+}