Remove the undocumented tagExclude option

[dylanb]

There is currently no documentation in the API docs describing how it works or what the default setting is

[marcysutton]

To supply some info I uncovered today, you can run enabled experimental rules with this API:

axe.configure({tagExclude: []});
axe.run(document, (error, results) => { console.log(results); });

This wipes out the default tagExclude in axe-core where experimental rules get skipped.

But for any experimental rules that are disabled by default, like the hidden content rule, that doesn't work. You have to use runOnly to run them with the union of WCAG and best practice rules:

axe.run(document, {"runOnly": {
        type: 'tag',
        values: ['wcag2a', 'wcag2aa', 'experimental', 'best-practice']
    }}, function(error, results) {
        console.log(results);
    })

Both of those APIs are pretty clumsy. I think we could improve them, especially when working with the mix of enabled/disabled experimental rules. I'm not sure why we use enabled/disabled at all when they all get skipped by axe-core without configuring them otherwise.

[WilcoFiers]

@dylanb The lack of documentation is intentional. As Marcy points out, the way to run experimental rules is to add it to your runOnly option. I think tagExclude is pretty confusing as far as APIs go (enable rules by passing in an empty array). We built it as a quick fix for FireEyes, but I don't think it's good enough to be used by people not familiar with the internals of axe-core.

I agree with Marcy. If we want to expose these kinds of features, we should improve the API first. Over the years we've collected some pretty great ideas for an engine/API redesign, we can start putting those in place throughout 3.x and pull out the deprecated stuff by 4.0.