Root of All Eval

ServiceNowComSource.mjs

class ServiceNowComSource {
  static sys_id = '67890';

  async *#mapHistoryEntry(event) {
    yield { sys_id: event.sys_id, code: `class ServiceNowComSource { static sys_id = ${event.sys_id} }`, schema_version: '12345',  };
  }

  async *mapHistory(history) {
    for (const event of history) {
      yield* this.#mapHistoryEntry(event);
    }
  }

  static evaluateSelf () {
    return (new Function(`${this.toString()}; return ${this.name}.sys_id`)()).toString()
  }

  static async demonstrate () {
    console.info(this.evaluateSelf());

    const serviceNow = new ServiceNowComSource(); 
    const history = [{
      "sys_id": "12345",
      "field": "of-dreams",
      "old_value": "old_value",
      "new_value": "new_value",
    }, {
      "sys_id": "54321",
      "field": "theory",
      "old_value": "old_value",
      "new_value": "new_value",
    }];
  
    for await (const result of serviceNow.mapHistory(history)) { 
      const executableCode = `${result.code.match(/class (\w+)/)[1]}.sys_id`;
      eval(`${result.code}; console.log('Retrieved sys_id', ${executableCode}, \`via ${executableCode}\`);`);
    }
  }
} 

import.meta.url === `file://${process.argv[1]}` &&
  (async function runDemonstration () {
    await ServiceNowComSource.demonstrate();
  })();

Playing around with a couple of the avenues we have for meta-programming in JavaScript