Microsoft's JavaScript team has stated that: "Some examples, like Dart,
portend that JavaScript has fundamental flaws and to support these scenarios
requires a 'clean break' from JavaScript in both syntax and runtime. We
disagree with this point of view."[25] Microsoft later released a JavaScript
superset language, TypeScript.[26]
Apple engineer Oliver Hunt, working on the WebKit project (which, at the
time, powered both Safari and Google's own Chrome browser) stated:
Adding an additional web facing language (that isn't standardized) doesn't
seem beneficial to the project, if anything it seems harmful (cf. VBScript
in IE).[27]
[...] Adding direct and exposed support for a non-standard language [Dart]
is hostile to the open web—by skipping any form [of] 'consensus' driven
language development that might happen, and foisting whatever language we
want on the Web instead. This implicitly puts any browser that supports
additional proprietary extensions in the same position as a browser
supporting something like VBScript, and has the same effect: breaking the
open web by making content that only works effectively in a single product.