Using swc to transpile typescript to javascript. Am I missing something? #9811

kratess · 2024-12-25T10:27:26Z

kratess
Dec 25, 2024

Here is my code.

#[macro_use]
extern crate swc_common;
extern crate swc_ecma_parser;
use std::fs::File;
use std::path::Path;

use swc_common::sync::Lrc;
use swc_common::{
    errors::{ColorConfig, Handler},
    SourceMap,
};
use swc_ecma_codegen::text_writer::JsWriter;
use swc_ecma_codegen::Emitter;
use swc_ecma_parser::{lexer::Lexer, Parser, StringInput, Syntax};

fn main() {
    let cm: Lrc<SourceMap> = Default::default();
    let handler = Handler::with_tty_emitter(ColorConfig::Auto, true, false, Some(cm.clone()));

    let fm = cm
        .load_file(Path::new("input.ts"))
        .expect("failed to load test.ts");

    let lexer = Lexer::new(
        Syntax::Typescript(Default::default()),
        swc_ecma_ast::EsVersion::Es2024,
        StringInput::from(&*fm),
        None,
    );

    let mut parser = Parser::new_from(lexer);

    for e in parser.take_errors() {
        e.into_diagnostic(&handler).emit();
    }

    let _module = parser
        .parse_module()
        .map_err(|mut e| {
            // Unrecoverable fatal error occurred
            e.into_diagnostic(&handler).emit()
        })
        .expect("failed to parser module");

    // Create a file for output
    let mut file = File::create("output.js").expect("Failed to create file");

    // Create the JsWriter for writing the output to the file
    let writer = JsWriter::new(cm.clone(), "\n", &mut file, None); // Use the file as the writer
    let mut emitter = Emitter {
        cfg: Default::default(),
        cm: cm.clone(),
        wr: writer,
        comments: None,
    };
    emitter
        .emit_module(&_module)
        .expect("failed to emit module");
}

my typescript code gets converted again to typescript. Am I missing something? The documentation is very scarse :(