dart compile

This guide describes how to use the dart compile command to compile a Dart program to a target platform.

Use the dart compile command to compile a Dart program to a target platform. The output—which you specify using a subcommand—can either include a Dart runtime or be a module (also known as a snapshot).

Here's an example of using the exe subcommand to produce a self-contained executable file (myapp.exe):

dart compile exe bin/myapp.dart
Generated: /Users/me/myapp/bin/myapp.exe

The next example uses the aot-snapshot subcommand to produce an ahead-of-time (AOT) compiled module (myapp.aot). It then uses the dartaotruntime command (which provides a Dart runtime) to run the AOT module:

dart compile aot-snapshot bin/myapp.dart
Generated: /Users/me/myapp/bin/myapp.aot
dartaotruntime bin/myapp.aot

To specify the path to the output file, use the -o or --output option:

dart compile exe bin/myapp.dart -o bin/runme

For more options and usage information, run dart compile [<subcommand>] --help:

dart compile exe --help

The dart compile command replaces the dart2native, dart2aot, and dart2js commands.

Refer to the native_app sample for a simple example of using dart compile to compile a native app, followed by examples of running the app.

The following table shows the subcommands of dart compile.

The following sections have details about each type of output that dart compile can produce.

The exe subcommand produces a standalone executable for Windows, macOS, or Linux. A standalone executable is native machine code that's compiled from the specified Dart file and its dependencies, plus a small Dart runtime that handles type checking and garbage collection.

You can distribute and run the output file like you would any other executable file.

Compile your app and set the output file:

dart compile exe bin/myapp.dart -o /tmp/myapp

When successful, this command outputs the following:

Generated: /tmp/myapp

Run your compiled app from the /tmp directory:

./tmp/myapp

Cross-compilation to Linux x64 and ARM64 is supported on the following 64-bit host operating systems: macOS, Windows, and Linux.

To use cross-compilation, include the following flags:

--target-os=linux

The target operating system for the compiled executable. The Linux operating system is supported at this time.

--target-arch=value

The target architecture for the compiled executable. The value for this flag can be arm64 (64-bit ARM processor) or x64 (x86-64 processor).

The following command demonstrates how to cross-compile a standalone executable for a 64-bit Linux system:

dart compile exe \
  --target-os=linux \
  --target-arch=x64 \
  hello.dart

Internally, this command downloads additional Dart SDK binaries and caches them in the ~/.dart directory.

Here's a sample output with the --verbose flag specified with the command:

Downloading https://storage.googleapis.com/dart-archive/channels/dev/signed/hash/...4864.../sdk/gen_snapshot_macos_arm64_linux_x64...
Downloading https://storage.googleapis.com/dart-archive/channels/dev/raw/hash/...64e44.../sdk/dartaotruntime_linux_x64...
Specializing Platform getters for target OS linux.
Generating AOT kernel dill.
Compiling /tmp/hello.dart to /tmp/hello.exe using format Kind.exe:
Generating AOT snapshot. path/to/dir/.dart/3.8.0-265.0.dev/gen_snapshot_macos_arm64_linux_x64 []
Generating executable.
Marking binary executable.
Generated: /tmp/hello.exe

Executables created with dart compile exe support signing on macOS and Windows.

To learn more about platform-specific code signing, see the platform documentation for those operating systems:

• Windows SignTool.exe documentation
• Apple Code Signing guide

The exe subcommand has the following known limitations:

• No support for dart:mirrors and dart:developer. For a complete list of the core libraries you can use, reference the Multi-platform and Native platform library tables.

• Cross-compilation is supported, but the target OS is limited to Linux. To learn more, check out Cross-compilation.

Use AOT modules to reduce disk space requirements when distributing multiple command-line apps. The aot-snapshot subcommand produces an output file specific to the current architecture on which you compile your app.

For example, if you use macOS to create a .aot file, then that file can run on macOS only. Dart supports AOT modules on Windows, macOS, and Linux.

Compile your app and set the output file:

dart compile aot-snapshot bin/myapp.dart

When successful, this command outputs the following:

Generated: /Users/me/myapp/bin/myapp.aot

Run your compiled app from the /bin directory:

dartaotruntime bin/myapp.aot

To learn more, see the dartaotruntime documentation.

Cross-compilation support for the aot-snapshot subcommand is the same as what's available for the exe subcommand. For more information, see Self-contained executables (exe).

The aot-snapshot subcommand has the same limitations as the exe subcommand. For more information, see Self-contained executables (exe)

JIT modules include all the parsed classes and compiled code that's generated during a training run of a program.

dart compile jit-snapshot bin/myapp.dart
Compiling bin/myapp.dart to jit-snapshot file bin/myapp.jit.
Hello world!
dart run bin/myapp.jit
Hello world!

When running from an application module, the Dart VM doesn't need to parse or compile classes and functions that were already used during the training run, so the VM starts running user code sooner.

These modules are architecture specific, unlike modules produced using the kernel subcommand.

Use the kernel subcommand to package up an app into a single, portable file that can be run on all operating systems and CPU architectures. A kernel module contains a binary form of the abstract syntax tree (Kernel AST) for a Dart program.

Here's an example of creating and running a kernel module:

dart compile kernel bin/myapp.dart
Compiling bin/myapp.dart to kernel file bin/myapp.dill.
dart run bin/myapp.dill

Although kernel modules have reduced startup time compared to Dart code, they can have much slower startup than architecture-specific AOT output formats.

The js subcommand compiles Dart code to deployable JavaScript.

The dart compile js command has multiple options to customize javascript code compilation.

• Basic options
• Path and environment options
• Display options
• Analysis options

Common options include:

-o <file> or --output=<file>

Generates the output into <file>. If not specified, the output goes in a file named out.js.

--enable-asserts

Enables assertion checking.

-O{0|1|2|3|4}

Controls optimizations to reduce file size and improve code performance. To learn more about these optimizations, run dart compile js -hv.

• -O0: Disables many optimizations.

• -O1: Enables default optimizations.

• -O2: Enables -O1 optimizations, plus additional ones (such as minification) that respect the language semantics and are safe for all programs.

• -O3: Enables -O2 optimizations, plus omits implicit type checks.

• -O4: Enables more aggressive optimizations than -O3, but with the same assumptions.

--no-source-maps

Do not generate a source map file.

-h or --help

Displays help. To get information about all options, use -hv.

Some other handy options include:

--packages=<path>

Specifies the path to the package resolution configuration file. For more information, check out the Dart package configuration file specification.

-D<flag>=<value>

Defines an environment declaration and value pair which can be accessed with String.fromEnvironment, int.fromEnvironment, bool.fromEnvironment, or bool.hasEnvironment. To learn more about environment declarations, see Configuring apps with compilation environment declarations.

--version

Displays version information for dart.

The following options help you control the compiler output.

--suppress-warnings

Doesn't display warnings.

--suppress-hints

Doesn't display hints.

--terse

Emits diagnostics, without suggesting how to get rid of the diagnosed problems.

-v or --verbose

Displays lots of information.

The following options control the analysis performed on Dart code.

--fatal-warnings

Treat warnings as compilation errors.

--enable-diagnostic-colors

Adds colors to diagnostic messages.

--show-package-warnings

Shows warnings and hints generated from packages.

--csp

Disables dynamic generation of code in the generated output. This is necessary to satisfy CSP restrictions (see W3C Content Security Policy.)

--dump-info

Generates a file (with the suffix .info.json) that contains information about the generated code. You can inspect the generated file with tools in dart2js_info.

For example, to compile a Dart application to optimized JavaScript, run the following command:

dart compile js -O2 -o out/main.js web/main.dart

Follow these practices to improve type inference, reduce file size, and improve JavaScript performance:

• Don't use Function.apply().
• Don't override noSuchMethod().
• Avoid setting variables to null.
• Be consistent with the types of arguments you pass into each function or method.

To learn more about building and deploying JavaScript applications, check out Web deployment.