counterfact/dist/server/convert-js-extensions-to-cjs.js

a library for building a fake REST API for testing

import { namedTypes, visit } from "ast-types";
import { parse, print } from "recast";
export function convertFileExtensionsToCjs(code) {
    const ast = parse(code);
    // Visit the nodes in the AST looking for `require` calls
    visit(ast, {
        // Identify the CallExpression nodes
        visitCallExpression(path) {
            const { node } = path;
            // Check if it's a require call
            if (namedTypes.CallExpression.check(node) &&
                node.callee.type === "Identifier" &&
                node.callee.name === "require" &&
                node.arguments[0] !== undefined &&
                node.arguments[0].type === "Literal" &&
                typeof node.arguments[0].value === "string" &&
                node.arguments[0].value.startsWith(".")) {
                // Change the module string from "foo.js" to "foo.cjs"
                node.arguments[0].value = node.arguments[0].value.replace(
                // eslint-disable-next-line regexp/prefer-named-capture-group
                /(\.js|\.ts)?$/u, ".cjs");
            }
            // Continue traversing the AST
            this.traverse(path);
        },
    });
    return print(ast).code;
}