This is an ES5 feature

When do I get this error?

This is one of many generic error messages uses by JSLint in a number of situations. Most of these cases are covered in detail by dedicated articles. Following is a list of situations that will cause JSLint to generate this message. Where possible the cause is linked to a more detailed page:

About the author

James Allardice

This article was written by James Allardice, Software engineer at Tesco and orangejellyfish in London. Passionate about React, Node and writing clean and maintainable JavaScript. Uses linters (currently ESLint) every day to help achieve this.