Multiline function arguments with trailing comma - SyntaxError: Unexpected token )

[davegri]

• Version: v7.5.0
• Platform: Darwin Johns-MacBook-Pro.local 16.1.0 Darwin Kernel Version 16.1.0: Wed Oct 19 20:31:56 PDT 2016; root:xnu-3789.21.4~4/RELEASE_X86_64 x86_64

The following code:

function foo(a, b) { }
foo(
  'a',
  'b',
);

throws a syntax error:

);
^
SyntaxError: Unexpected token )
    at Object.exports.runInThisContext (vm.js:73:16)
    at Module._compile (module.js:543:28)
    at Object.Module._extensions..js (module.js:580:10)
    at Module.load (module.js:488:32)
    at tryModuleLoad (module.js:447:12)
    at Function.Module._load (module.js:439:3)
    at Module.require (module.js:498:17)
    at require (internal/module.js:20:19)

I would like to be able to comply with the airbnb style guide which requires a trailing comma

[vsemozhetbyt]

@davegri If I get it right, the airbnb rule imply Bebel transpiling for now. Even the last v8 version (5.7) does not support trailing commas in function parameter lists and calls yet. However, you can use --harmony_trailing_commas flag (v8 comment: "enable "harmony trailing commas in function parameter lists" (in progress)").

[joyeecheung]

Closing as not a bug. Node core would support trailing comma by default when V8 turns it on by default, right now the --harmony_trailing_commas flag is required.

[vsemozhetbyt]

It seems V8 5.8 will support them without a flag: these trailing commas are OK in the current Chrom Canary with V8 5.8.

[DanielRamosAcosta]

In which version of node is supported?

[vsemozhetbyt]

From Node.js 8 (at least in the last 08.11.1 it is supported).