> There is nothing about JavaScript that is uniquely suited to the browser
There are, however, features about JS VMs that make them (almost) uniquely suited to browsers. Most notably, almost any other VM has a stdlib including things like open() for local system files — and that'd be considered a massive security exploit. Some languages have features (v. parts of the stdlib) that are insecure in the browser setting — for example the backticks operator in Python. Ensuring an existing VM has had all access to the local system closed off could easily turn into a massive project in and of itself.
> It's hard enough to get browser vendors to agree to standards at all, say nothing about multiple standards for a single feature.
I don't think that's fair — I don't think there's many cases of major browser vendors acting maliciously towards standards in recent times, the only particular examples that stands out to me are the whole pointer/touch events debacle (with Apple withholding patents from the W3C Patent Grant) and the AV codecs mess with various vendors acting selfishly. Otherwise, almost everything seems to be genuine disagreements about how best to do things, especially given market realities.
There are, however, features about JS VMs that make them (almost) uniquely suited to browsers. Most notably, almost any other VM has a stdlib including things like open() for local system files — and that'd be considered a massive security exploit. Some languages have features (v. parts of the stdlib) that are insecure in the browser setting — for example the backticks operator in Python. Ensuring an existing VM has had all access to the local system closed off could easily turn into a massive project in and of itself.
> It's hard enough to get browser vendors to agree to standards at all, say nothing about multiple standards for a single feature.
I don't think that's fair — I don't think there's many cases of major browser vendors acting maliciously towards standards in recent times, the only particular examples that stands out to me are the whole pointer/touch events debacle (with Apple withholding patents from the W3C Patent Grant) and the AV codecs mess with various vendors acting selfishly. Otherwise, almost everything seems to be genuine disagreements about how best to do things, especially given market realities.