What does it mean to be "web-compatible"?

I got curious after reading the Array.prototype.contains thread.

I understand it means 'old things on the Web will break', but is there some
cutoff? Based on number sites or number of affected users?

Couldn't find a definition searching esdiscuss.org - apologies if it's been
discussed.

Cheers!
Adam
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On Tue, Oct 7, 2014 at 2:27 PM, Adam Ahmed <aahmed at atlassian.com> wrote:
> I got curious after reading the Array.prototype.contains thread.
>
> I understand it means 'old things on the Web will break', but is there some
> cutoff? Based on number sites or number of affected users?
>
> Couldn't find a definition searching esdiscuss.org - apologies if it's been
> discussed.

No official cut-off.  The strict definition is "whatever amount of
breakage browsers are willing to tolerate", which varies from
browser-to-browser and somewhat randomly anyway.  In Blink, for
example, we tend to be okay with breaking things around a .001%
cutoff.

~TJ

Thanks! 0.001% of what?
On 08/10/2014 8:33 AM, "Tab Atkins Jr." <jackalmage at gmail.com> wrote:

> On Tue, Oct 7, 2014 at 2:27 PM, Adam Ahmed <aahmed at atlassian.com> wrote:
> > I got curious after reading the Array.prototype.contains thread.
> >
> > I understand it means 'old things on the Web will break', but is there
> some
> > cutoff? Based on number sites or number of affected users?
> >
> > Couldn't find a definition searching esdiscuss.org - apologies if it's
> been
> > discussed.
>
> No official cut-off.  The strict definition is "whatever amount of
> breakage browsers are willing to tolerate", which varies from
> browser-to-browser and somewhat randomly anyway.  In Blink, for
> example, we tend to be okay with breaking things around a .001%
> cutoff.
>
> ~TJ
>
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On Tue, Oct 7, 2014 at 3:01 PM, Adam Ahmed <aahmed at atlassian.com> wrote:
> Thanks! 0.001% of what?

Page views, more or less.

~TJ