javascript – Browserify, Babel 6, Gulp – Unexpected token on spread operator-ThrowExceptions

Exception or error:

I’m trying to get my Browserify/Babelify/Gulp working in my project, but it won’t take the spread operator.

I got this error from my gulpfile:

[SyntaxError: /Users/mboutin2/Desktop/Todo-tutorial/src/reducers/grocery-list-reducers.js: Unexpected token (16:8) while parsing file: /Users/mboutin2/Desktop/Todo-tutorial/src/reducers/grocery-list-reducers.js]

This is my gulpfile.js

var gulp = require('gulp');
var source = require('vinyl-source-stream');
var browserify = require('browserify');
var sourcemaps = require('gulp-sourcemaps');
var uglify = require('gulp-uglify');
var buffer = require('vinyl-buffer');
var babelify = require('babelify');

gulp.task('build', function () {
  return browserify({entries: './src/client/app.js', extensions: ['.js'], debug: true})
    .transform(babelify, {presets: ['es2015', 'react']})
    .bundle()
    .on('error', function (err) {
      console.error(err);
      this.emit('end');
    })
    .pipe(source('app.min.js'))
    .pipe(buffer())
    .pipe(sourcemaps.init({loadMaps: true}))
    .pipe(uglify())
    .pipe(sourcemaps.write('./'))
    .pipe(gulp.dest('./public/js'));
});

gulp.task('default', ['build']);

I tried to create a .babelrc file, but it do the same thing. And my script works when i delete the spread operator.

This is the file where the Unexpected token occurs (quite simple).

import utils from '../utils/consts';

const initialState = {
  itemList: [
    {name: 'Apple', type: 'Fruit'},
    {name: 'Beef', type: 'Meat'}
  ]
};

export function groceryList(state = initialState, action = {}) {

  switch(action.type) {

    case utils.ACTIONS.ITEM_SUBMIT:
      return {
        ...state,
        itemList: [
          ...state.itemList,
          {name: action.name, type: action.itemType}
        ]
      };

    default:
      return state;

  }
}

I don’t know what doesn’t work in this, i read some issues on Github and the setup page on Babel website, but i can’t make it work correctly.

Can anyone show me how to handle this correctly? Thank you

How to solve:

That syntax is an experimental proposed syntax for the future, it is not part of es2015 or react so you’ll need to enable it.

npm install --save-dev babel-plugin-transform-object-rest-spread

and add

"plugins": ["transform-object-rest-spread"]

into .babelrc alongside your existing presets.

Alternatively:

npm install --save-dev babel-preset-stage-3

and use stage-3 in your presets to enable all stage-3 experimental functionality.

###

I had the same issue, installed stage-2 plugin and modified my package.json file, which looks like below

"babel": {
    "presets": [
      "es2015",
      "react",
      "stage-2"
    ]
  }

###

Just as a side note, some text editors (in my case Mac Notes) will contract ... into an elepsis entity, which will fail validation, so be aware of that too…

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