The sourceFile read-only property of the DeprecationReportBody interface returns the path to the source file where the deprecated feature was used.

A string, or null if the path is not known.

In this example we create a new ReportingObserver to observe deprecation reports, then print the value of sourceFile to the console.

let options = {
  types: ["deprecation"],
  buffered: true,
};

let observer = new ReportingObserver((reports, observer) => {
  let firstReport = reports[0];
  console.log(firstReport.type); // deprecation
  console.log(firstReport.body.sourceFile);
}, options);