How to use the command 'swc' (with examples)

The swc command is a JavaScript and TypeScript compiler written in Rust. It is a tool that transpiles JavaScript and TypeScript code to a lower-level language that can be understood by various web browsers and JavaScript engines. This article will provide several examples of how to use the swc command in different scenarios.

Use case 1: Transpile a specified input file and output to stdout

Code:

swc path/to/file

Motivation: This use case is helpful when you want to quickly transpile a single JavaScript or TypeScript file without creating an output file. The transpiled code will be displayed in the terminal.

Explanation:

• swc: The command to invoke the swc compiler.
• path/to/file: The path to the input file that needs to be transpiled.

Example output: The transpiled JavaScript or TypeScript code will be displayed in the terminal.

Use case 2: Transpile the input file every time it is changed

Code:

swc path/to/file --watch

Motivation: When working on a project, it can be tedious to manually run the swc command every time a file is modified. Setting the --watch flag makes the swc command continuously monitor the specified input file for changes and automatically transpile it whenever it is modified.

Explanation:

• --watch: The flag to enable the watch mode, which allows the command to continuously monitor the specified input file for changes.

Example output: The swc command will transpile the input file every time it is changed, and the updated JavaScript or TypeScript code will be displayed in the terminal.

Use case 3: Transpile a specified input file and output to a specific file

Code:

swc path/to/input_file --out-file path/to/output_file

Motivation: When you want to transpile a single JavaScript or TypeScript file and save the output into a specified file, this use case comes in handy.

Explanation:

• path/to/input_file: The path to the input file that needs to be transpiled.
• --out-file: The flag followed by the path to the output file where the transpiled code will be saved.
• path/to/output_file: The path to the output file where the transpiled code will be saved.

Example output: The swc command will transpile the input file and save the transpiled JavaScript or TypeScript code into the specified output file.

Use case 4: Transpile a specified input directory and output to a specific directory

Code:

swc path/to/input_directory --out-dir path/to/output_directory

Motivation: This use case is suitable when you want to transpile multiple JavaScript or TypeScript files from a specific directory and save the transpiled files to another directory.

Explanation:

• path/to/input_directory: The path to the input directory containing JavaScript or TypeScript files that need to be transpiled.
• --out-dir: The flag followed by the path to the output directory where the transpiled files will be saved.
• path/to/output_directory: The path to the output directory where the transpiled JavaScript or TypeScript files will be saved.

Example output: The swc command will transpile all the JavaScript or TypeScript files in the input directory and save the transpiled files into the specified output directory.

Use case 5: Transpile a specified input directory using a specific configuration file

Code:

swc path/to/input_directory --config-file path/to/.swcrc

Motivation: When you have a specific configuration file for the swc command, and you want to transpile multiple JavaScript or TypeScript files from a directory using that configuration, this use case will be useful.

Explanation:

• path/to/input_directory: The path to the input directory containing JavaScript or TypeScript files that need to be transpiled.
• --config-file: The flag followed by the path to the specific configuration file (.swcrc) that will be used for transpiling.
• path/to/.swcrc: The path to the specific configuration file (.swcrc) that contains the configuration options for the swc command.

Example output: The swc command will use the configuration options specified in the .swcrc file to transpile all the JavaScript or TypeScript files in the input directory.

Use case 6: Ignore files in a directory specified using glob path

Code:

swc path/to/input_directory --ignore ignored_files

Motivation: Sometimes, you may want to exclude specific files in a directory from being transpiled. This use case allows you to ignore certain files while transpiling all other JavaScript or TypeScript files in the directory.

Explanation:

• path/to/input_directory: The path to the input directory containing JavaScript or TypeScript files that need to be transpiled.
• --ignore: The flag followed by the glob path or specific file names to be ignored during transpilation.
• ignored_files: A glob path or specific file names to be ignored during transpilation.

Example output: The swc command will transpile all JavaScript or TypeScript files in the input directory except for the files specified in the ignored_files.