transform() — react Function Reference

Architecture documentation for the transform() function in print-warnings.js from the react codebase.

Function javascript BabelCompiler Entrypoint

Entity Profile

BabelCompiler→ Entrypoint→ transform() — react Function Reference

Dependency Diagram

graph TD
  561fc100_5fe6_4078_fbeb_f8197f0fe5c6["transform()"]
  685d06fd_98ba_ca14_0dfa_e332611ca26a["print-warnings.js"]
  561fc100_5fe6_4078_fbeb_f8197f0fe5c6 -->|defined in| 685d06fd_98ba_ca14_0dfa_e332611ca26a
  style 561fc100_5fe6_4078_fbeb_f8197f0fe5c6 fill:#6366f1,stroke:#818cf8,color:#fff

Relationship Graph

Source Code

scripts/print-warnings/print-warnings.js lines 21–66

function transform(file, enc, cb) {
  fs.readFile(file.path, 'utf8', function (err, source) {
    if (err) {
      cb(err);
      return;
    }

    let ast;
    try {
      ast = parse(source);
    } catch (error) {
      console.error('Failed to parse source file:', file.path);
      throw error;
    }

    traverse(ast, {
      enter() {},
      leave(node) {
        if (node.type !== 'CallExpression') {
          return;
        }
        const callee = node.callee;
        if (
          callee.type === 'MemberExpression' &&
          callee.object.type === 'Identifier' &&
          callee.object.name === 'console' &&
          callee.property.type === 'Identifier' &&
          (callee.property.name === 'warn' || callee.property.name === 'error')
        ) {
          // warning messages can be concatenated (`+`) at runtime, so here's
          // a trivial partial evaluator that interprets the literal value
          try {
            const warningMsgLiteral = evalStringConcat(node.arguments[0]);
            warnings.add(warningMsgLiteral);
          } catch {
            // Silently skip over this call. We have a lint rule to enforce
            // that all calls are extractable, so if this one fails, assume
            // it's intentional.
          }
        }
      },
    });

    cb(null);
  });
}