Function enter

packages/commonjs/src/transform-commonjs.js:112–420

(node, parent)

  walk(ast, {
    enter(node, parent) {
      if (skippedNodes.has(node)) {
        this.skip();
        return;
      }

      if (currentTryBlockEnd !== null && node.start > currentTryBlockEnd) {
        currentTryBlockEnd = null;
      }
      if (currentConditionalNodeEnd !== null && node.start > currentConditionalNodeEnd) {
        currentConditionalNodeEnd = null;
      }
      if (currentConditionalNodeEnd === null && conditionalNodes.has(node)) {
        currentConditionalNodeEnd = node.end;
      }

      programDepth += 1;
      if (node.scope) ({ scope } = node);
      if (functionType.test(node.type)) lexicalDepth += 1;
      if (sourceMap) {
        magicString.addSourcemapLocation(node.start);
        magicString.addSourcemapLocation(node.end);
      }

      // eslint-disable-next-line default-case
      switch (node.type) {
        case 'AssignmentExpression':
          if (node.left.type === 'MemberExpression') {
            const flattened = getKeypath(node.left);
            if (!flattened || scope.contains(flattened.name)) return;

            const exportsPatternMatch = exportsPattern.exec(flattened.keypath);
            if (!exportsPatternMatch || flattened.keypath === 'exports') return;

            const [, exportName] = exportsPatternMatch;
            uses[flattened.name] = true;

            // we're dealing with `module.exports = ...` or `[module.]exports.foo = ...` –
            if (flattened.keypath === 'module.exports') {
              moduleExportsAssignments.push(node);
              if (programDepth > 3) {
                moduleAccessScopes.add(scope);
              } else if (!firstTopLevelModuleExportsAssignment) {
                firstTopLevelModuleExportsAssignment = node;
              }
            } else if (exportName === KEY_COMPILED_ESM) {
              if (programDepth > 3) {
                shouldWrap = true;
              } else {
                // The "type" is either "module" or "exports" to discern
                // assignments to module.exports vs exports if needed
                topLevelDefineCompiledEsmExpressions.push({ node, type: flattened.name });
              }
            } else {
              const exportsAssignments = exportsAssignmentsByName.get(exportName) || {
                nodes: [],
                scopes: new Set()
              };