Reporting a bug

Where to Find Known Issues

We are using GitHub Issues for tracking any bugs. Before filing a new bug, please try to make sure a GitHub issue does not already exist for it.

Security Bugs

Polyfill.io has a bounty program for the safe disclosure of security bugs. With that in mind, please do not file public issues; go through the process outlined on that page.

Reporting New Issues

The sections below outline some common scenarios and how to help create good bug reports for them.

The polyfill bundle is causing an error in your app

You've got an error in your website that you've tracked down to the code you're loading from the polyfill service.

The best way to get your bug fixed is to provide a reduced test case. We ask for a reduced test case because occassionally the problem is not from polyfill.io but from the host website's code.

Raise a new issue on our issue tracker, and include:

  • A description of the problem. I.E what you expected to happen, and what actually did happen.
  • A link to your reduced test case using an online tool like JSBin, which loads only the polyfill.io script, and then includes the least amount of code required to trigger the problem. Disable any browser plugins when you are testing, this will help you be sure that you are only running the code in your reduced test case.
  • The exact name and version number of the browser that the problem occurs within.
  • If relevant, a screenshot of the console output or of the problem.

A polyfill is not correctly/completely emulating the missing feature

You've found a polyfill which you believe is not working correctly.

The best way to get your bug fixed is to provide a reduced test case. We ask for a reduced test case because occassionally the problem is not from polyfill.io but from the host website's code.

Raise a new issue on our issue tracker, and include:

  • A description of the problem. I.E what you expected to happen, and what actually did happen.
  • A link to the specification documentation that defines the behaviour that is missing in the polyfill. I.E. ECMA-262 and WHATWG.
  • A link to your reduced test case using an online tool like JSBin, which loads only the polyfill.io script, and then includes the least amount of code required to trigger the problem. Disable any browser plugins when you are testing, this will help you be sure that you are only running the code in your reduced test case.
  • The exact name and version number of the browser that the problem occurs within.
  • If relevant, a screenshot of the console output or of the problem.
  • If a browser exists which has the feature natively ans does not have the same problem when running your reduced test case, a screenshot of the browser and the exact name and version number.

A particular polyfill is being served to a browser that does not require the polyfill

You've found that a browser is being served a polyfill for a feature that it does not need.

Raise a new issue on our issue tracker, and include:

  • A link to reliable sources of browser support information such as MDN, Can I Use and Kangax's compatability table which shows that the browser should support the feature.
  • An explanation of how you have tested support of the feature in the browser. Screenshots of the browser using the feature is an excellent way of showing support of the feature.