When do I get this error?

The "ES5 option is now set per default" error is thrown when JSHint (version 2.0.0 and above only) encounters the es5 option with a value of true. Here's an example in which we set the es5 option so we can use reserved words as property identifers (which was not allowed in ES3):

/*jshint es5: true */
var x = {
    default: 10
};

Why do I get this error?

This error is raised to highlight a *pointless piece of code. If you're using JSHint 2.0.0 or above, the es5 option will be set to true by default, due to the fact that environments supporting the ES5 spec are now far more widespread.

You can simply remove the option from any JSHint directives or .jshintrc files. Select JSHint version 1.1.0 or below in the following example to see the difference from when the es5 option was not on by default:

var x = {
    default: 10
};

In JSHint 1.0.0 and above you have the ability to ignore any warning with a special option syntax. Since this is an informational JSHint message, it cannot be disabled.