Babel, Unexpected token (15:33) ::

Question

I am experimenting with cycle-blessed, with the example js code provided on its GitHub page, but am experiencing issues.

import { run } from '@cycle/core';
import blessed from 'blessed';
import { makeTermDriver, box } from 'cycle-blessed';
import { Observable as $ } from 'rx';

let screen = blessed.screen({ smartCSR: true, useBCE: true, title:    
'Hello, World!' });
let BlueBox = text => box({ border: { type: 'line', fg: 'blue' } },
text);         

run(({ term }) => ({
term: $.just(BlueBox('Hello, World!')),
exit: term.on('key C-c')
}), {
term: makeTermDriver(screen),
exit: exit$ => exit$.forEach(::process.exit)
});

I believe that this code can be ran with Babel, but trying to run:

 ./node_modules/.bin/babel src -d dest

results in:

13 | }), {
14 |     term: makeTermDriver(screen),
15 |     exit: exit$ => exit$.forEach(::process.exit)
   |                                  ^
16 | });

Am I correct in thinking babel can be used to transpile this code?

Any help appreciated.

.babelrc:

{
"presets": ["es2015"]
}
{
"plugins": ["transform-function-bind"]

}

Answer 1

:: is an experimental function syntax which performs function binding and method extraction.

To transpile the code using this operator it you need to install and add a transform-function-bind plugin to your .babelrc file.

First install it from npm:

$ npm install babel-plugin-transform-function-bind

Then change your .babelrc file to this:

{
  "presets": ["es2015"],
  "plugins": ["transform-function-bind"]
}