Symbol support (#11268)
* Allow rest/spread on polyfilled or builtin iterables when `Symbol` unsupported Currently, when `Symbol` is not supported, we allow using rest/spread with: - arrays - strings - arguments With this PR, it will be also possible to use it with - maps - sets - binary arrays While in old browsers es6 builtins would still need to be polyfilled, it's way easier to polyfill them because `Symbol` cannot be reliably polyfilled. I didn't use `instanceof` becase: - it doesn't work with polyfills not attatched to the global scope - when using Babel to load polyfills, it would force the inclusion of `Map` and `Set` polyfills even if they are not used Downside: the current approach of relying on `toString || construcor.name` doesn't work with subclasses. * Don't use Array.from for array-like objects
The compiler for writing next generation JavaScript.
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Babel is a tool that helps you write code in the latest version of JavaScript. When your supported environments don't support certain features natively, Babel will help you compile those features down to a supported version.
In
// ES2015 arrow function
[1, 2, 3].map((n) => n + 1);
Out
[1, 2, 3].map(function(n) {
return n + 1;
});
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