Type must have a '[Symbol.iterator]()' method error for ...x where x: T[] with "target": "es2018".

[earshinov]

TypeScript Version: 2.8.0-dev.20180321

Search Terms: Symbol.Iterator, compilerOptions, compilerOptions.lib, es6, es2018, default, lib

Code

(function() {
    var a = [4, 5, 6];
    var b = [1, 2, 3];
    a.push(...b);
})();

tsconfig.json:

{
    "compilerOptions": {
        "target": "es2018"
    }
}

Expected behavior:
No errors

Actual behavior:

src/index.ts(4,15): error TS2488: Type must have a '[Symbol.iterator]()' method that returns an iterator.

No errors when compiled with "target": "es6" in tsconfig.json

Playground Link:
The issue is not reproducible in the playground as it does not take a tsconfig.

Related Issues:
None as far as I know.

[earshinov]

Presumably, the defaults for lib described on the Compiler Options page do not work for "es2018".

When I explicitly configure "lib": [ "dom", "es6", "dom.iterable", "scripthost" ] in tsconfig.json, the code compiles without any errors.

[mhegazy]

--target es2018 is not supported yet. it is tracked by #20463.

So the closest you can get to this is --target es2017 --lib es2018,dom,dom.iterable

[earshinov]

@mhegazy Thank you for the information. I guess this ticket should be left open in order to check if everything works when --es2018 support is complete.

[mhegazy]

We already have one issue tracking it in #20463. ideally we would keep one ticket per issue.

[earshinov]

OK, closing then. For now we switched back to es6 instead of es2018.