Add line numbers to js errors

index.d.ts

@@ -47,3 +47,31 @@ export class Preprocessor {
 */
   parse(src: string, filename?: string): Parsed[];
 }
+
+export interface ParseError {
+  /**
+   * Formatted output for CLI
+   */
+  source_code: string;
+  /**
+   * Color-Formatted output for CLI
+   */
+  source_code_color: string;
+
+  /**
+   * 0-indexed starting line of the error
+   */
+  start_line: number;
+  /**
+   * 0-indexed starting byte-based column of the error
+   */
+  start_column: number;
+  /**
+   * 0-indexed ending line of the error
+   */
+  end_line: number;
+  /**
+   * 0-indexed ending byte-based column of the error
+   */
+  end_column: number;
+}

src/bindings.rs

@@ -69,9 +69,23 @@ fn as_javascript_error(err: swc_ecma_parser::error::Error, source_map: Lrc<Sourc
     js_sys::Reflect::set(
         &js_err,
         &"source_code_color".into(),
-        &capture_err_detail(err, source_map, GraphicalTheme::unicode()),
+        &capture_err_detail(err.clone(), source_map.clone(), GraphicalTheme::unicode()),
     )
     .unwrap();
+
+    let lo = source_map.lookup_char_pos_adj(err.span().lo);
+    let hi = source_map.lookup_char_pos_adj(err.span().hi);
+
+    let start_line = lo.line;
+    let start_column = lo.col.0;
+    let end_line = hi.line;
+    let end_column = hi.col.0;
+
+    js_sys::Reflect::set(&js_err, &"start_line".into(), &start_line.into()).unwrap();
+    js_sys::Reflect::set(&js_err, &"start_column".into(), &start_column.into()).unwrap();
+    js_sys::Reflect::set(&js_err, &"end_line".into(), &end_line.into()).unwrap();
+    js_sys::Reflect::set(&js_err, &"end_column".into(), &end_column.into()).unwrap();
+
     return js_err;
 }
 

test/node-api-esm.mjs

@@ -62,4 +62,40 @@ export default template(\`Hi\`, {
       .to.have.property("source_code_color")
       .matches(/Expected ident.*[\u001b].*class \{/s);
   });
+
+  it("Offers line on parse errors", function () {
+    let parseError;
+    try {
+      p.process(`class {`);
+    } catch (err) {
+      parseError = err;
+    }
+
+    expect(parseError.start_line).to.equal(1, "start_line");
+    expect(parseError.start_column).to.equal(6, "start_column");
+    expect(parseError.end_line).to.equal(1, "end_line");
+    expect(parseError.end_column).to.equal(7, "end_column");
+  });
+
+  it("Offers line on <template> parse errors", function () {
+    let parseError;
+    try {
+      p.process(`let foo = 2;
+
+const Foo = <template>{{foo}}</template>
+
+<template>
+  🥳🥳🥳🥳<Foo />
+`);
+    } catch (err) {
+      parseError = err;
+    }
+
+    // Unexpected eof
+    // column 14 is the EOF
+    expect(parseError.start_line).to.equal(6, "start_line");
+    expect(parseError.start_column).to.equal(18, "start_column");
+    expect(parseError.end_line).to.equal(6, "end_line");
+    expect(parseError.end_column).to.equal(18, "end_column");
+  });
 });