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Comment by skrebbel | Hacker News Reader

I don't understand why the author compares ES6 symbols to Ruby symbols; they're nothing alike. It's kind of the opposite: Ruby symbols are guaranteed to be the same object if they have the same name, ES6 symbols are guaranteed to be a different object, even if they have the same name (description)

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  s1 = Symbol.for('cat')
  s2 = Symbol.for('cat')
  s1 === s2  // true

The most common use-case for them is to generate symbols that don't collide, though.

`Symbol.for` uses a global registry and the whole thing is "stringly typed".

Looks like an anti-pattern to me.

If you want one particular symbol from some library, you could import it.

This was the one thing I didn't understand. Why is using a global Symbol registry any better than just using string properties like usual?

There won't be a problem if the string happens to be e.g. "toString", I guess. Although they added a 'Map' for that, too.

    s1 = Symbol("cat");
    s2 = Symbol.for("cat");
    s3 = Symbol.for("cat");
    s1 == s2; // false
    s2 == s3; // true

You can still have Symbols outside the registry.

That I understand. What I don't understand is why s2 and s3 shouldn't just be vanilla strings.

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