Symbols couldn't convert properly with String() method

[greybax]

The next statement should return true:

return String(Symbol("foo")) === "Symbol(foo)";

[weswigham]

This statement is always false - the lefthand side of the equality is not a string primitive, but rather a string object - string objects are only checked by reference equality. Since the right hand side is not a string object (its a string primitive), the two are never equal. This isn't a typescript thing - this is normal JS behavior.

[oleg-py]

@weswigham in JS when you call String(obj) without new, you get a primitive string, same as using obj+''

[johnfn]

@weswigham Typing that command into the Javascript console on Chrome (with the experimental Javascript flag on) returns true for me.

[saschanaz]

The same is true on Edge and Firefox.

[weswigham]

Op, sorry, I was mistaken - totally though I saw new. Though, as it turns out I'd be wrong anyway - calling new String on a symbol errors in chrome. In any case, TS doesn't do anything to polyfill symbols for you - wouldn't this be on CoreJS or whatever else you're using to polyfill them? I'm not sure there's anything TS-related here.

[DanielRosenwasser]

I believe that this either depends on your JS runtime or your polyfill, so this isn't TypeScript-specific.

[greybax]

@DanielRosenwasser this feature one of the required for full support of Symbols in TypeScript.
This issue also mentioned in compat-table/es6

[kitsonk]

@greybax but if you notice, it is not something that is down emittable to ES5. All the transpilers don't (cannot) support it, because it depends on the runtime engine behaving different in ES6.

[DanielRosenwasser]

@kitsonk is correct. Babel achieves this here by bundling core.js. We could also bundle core.js to achieve some of the runtime polyfills, but we'd prefer to avoid adding a dependency if possible and let users opt in to that on their own.

[greybax]

ok