Fetch polyfill with webpack

webpack.js

var webpack = require('webpack');
var HtmlWebpackPlugin = require('html-webpack-plugin');
var path = require('path');
var folders = {
    APP: path.resolve(__dirname, '../app'),
    BUILD: path.resolve(__dirname, '../build'),
    BOWER: path.resolve(__dirname, '../bower_components'),
    NPM: path.resolve(__dirname, '../node_modules')
};

var config = {
    entry: {
        app: [
            'webpack/hot/dev-server',
            "./js/app.js"
        ]
    },
    debug: true,
    resolve: {
        extensions: ['', '.js', '.jsx', '.scss'],
        alias: {
            //'es6-promise': path.join(folders.NPM, 'es6-promise', 'es6-promise.js'),
            //'fetch': path.join(folders.NPM, 'whatwg-fetch', 'fetch.js'),
        }
    },
    stats: {
        colors: true,
        reasons: true,
    },
    output: {
        path: __dirname + '/build',
        publicPath: '/',
        filename: '[name].[hash].js',
        chunkFilename: '[id].[hash].js'
    },
    module: {
        loaders: [
            {
                test: /\.s?css$/,
                exclude: /node_modules/,
                loaders: [
                    'style',
                    'css',
                    'autoprefixer?browsers=last 2 version',
                    'sass?' + ['outputStyle=nested'].join('&')
                ]
            },
            { test: /\.jsx?$/, loaders: ['react-hot', 'babel'], exclude: /node_modules/ },
            { test: /\.json$/, loader: 'json' },
        ]
    },
    plugins: [
        new webpack.HotModuleReplacementPlugin(),
        new webpack.ProvidePlugin({
            'Promise': 'es6-promise', // Thanks Aaron (https://gist.github.com/Couto/b29676dd1ab8714a818f#gistcomment-1584602)
            'fetch': 'imports?this=>global!exports?global.fetch!whatwg-fetch'
        }),
        //new webpack.optimize.CommonsChunkPlugin('app', null, false),
        new webpack.NoErrorsPlugin(),
        new HtmlWebpackPlugin({
            template: path.resolve('./', 'index.html'),
            webpackDevServer: '/webpack-dev-server.js'
        })
    ]
};

module.exports = config;

Was wondering the same thing…

babel-polyfill does not appear to include a fetch polyfill, so you'd still need to use this.

Wouldn't simply including it in entry be a better approach? There is actually a use case where the demonstrated method will fail, for example if you use Webpack server side with externals: [nodeExternals()], you would be forced to use entry anyways because external modules would not see fetch as being defined. So it seems it would be more consistent to use entry here as well.

After double checking, this approach is actually incorrect and will not polyfill fetch properly, the correct approach is to configure whatwg-fetch on your Webpack entry configuration, like such:

module.exports = {
   entry: ['whatwg-fetch', './app/js']
};

This will fix issues where using a 3rd party that expect fetch will not find it with the approach of this gist. This is also consistent with the way babel documents using a polyfill with Webpack and does not require the extra loaders.

I have opened a PR with fetch so they stop referring to this solution: JakeChampion/fetch#331

@Nosherwan @silvenon you should not include a Promise polyfill if you use babel-polyfill, the correct configuration would then be:

module.exports = {
   entry: ['babel-polyfill', 'whatwg-fetch', './app/js']
};

Has anyone had success adding this when entry is an object?

@simonsmith Does this not work for you?

entry: {
    demo: ['whatwg-fetch', './app']
  },

@tarikjn
Works for me too, thanks!

@Couto ganda truta! 👍

🐟

@tarikjn i am getting a Exception thrown and not caught in IE11 when i use babel-polyfill instead of es6 promise .

entry: ['babel-polyfill', 'whatwg-fetch','./src/main.js'],

but this works perfect in IE11

entry: ['es6-promise', 'whatwg-fetch','./src/main.js']

Is there a way to have the polyfills loaded from a seperated chunk?

I wish that when a browser is lacking a feature it loads the predeclared polyfill (which would be put in a chunk by webpack). So that the final bundle size does not contain all the polyfills.

Is this possible somehow?

@vikas5914, I'm getting the exact same. Did you solve this in the end, as I would rather keep using babel-polyfill

Adding polyfills through entry - defines them in global scope. If you own an application (SPA for example), I think It's Ok, but if you are working on the library, I don't recommend this approach.

if you use webpack 2 you need to change import -> import-loader and export -> export-loader

new webpack.ProvidePlugin({
  fetch: 'imports-loader?this=>global!exports-loader?global.fetch!whatwg-fetch'
})

Can we use webpack.ProvidePlugin to conditionally load polyfills? Essentially load polyfills if browser don't support natively.

+1

🥇

good job!

const webpack = require('webpack');
const HtmlWebpackPlugin = require('html-webpack-plugin');
const path = require('path');
const folders = {
    APP: path.resolve(__dirname, '../app'),
    BUILD: path.resolve(__dirname, '../build'),
    BOWER: path.resolve(__dirname, '../bower_components'),
    NPM: path.resolve(__dirname, '../node_modules')
};

const config = {
    entry: {
        app: [
            'webpack/hot/dev-server',
            "./js/app.js"
        ]
    },
    debug: true,
    resolve: {
        extensions: ['', '.js', '.jsx', '.scss'],
        alias: {
            //'es6-promise': path.join(folders.NPM, 'es6-promise', 'es6-promise.js'),
            //'fetch': path.join(folders.NPM, 'whatwg-fetch', 'fetch.js'),
        }
    },
    stats: {
        colors: true,
        reasons: true,
    },
    output: {
        path: __dirname + '/build',
        publicPath: '/',
        filename: '[name].[hash].js',
        chunkFilename: '[id].[hash].js'
    },
    module: {
        loaders: [
            {
                test: /\.s?css$/,
                exclude: /node_modules/,
                loaders: [
                    'style',
                    'css',
                    'autoprefixer?browsers=last 2 version',
                    'sass?' + ['outputStyle=nested'].join('&')
                ]
            },
            { test: /\.jsx?$/, loaders: ['react-hot', 'babel'], exclude: /node_modules/ },
            { test: /\.json$/, loader: 'json' },
        ]
    },
    plugins: [
        new webpack.HotModuleReplacementPlugin(),
        new webpack.ProvidePlugin({
            'Promise': 'es6-promise', // Thanks Aaron (https://gist.github.com/Couto/b29676dd1ab8714a818f#gistcomment-1584602)
            'fetch': 'imports?this=>global!exports?global.fetch!whatwg-fetch'
        }),
        //new webpack.optimize.CommonsChunkPlugin('app', null, false),
        new webpack.NoErrorsPlugin(),
        new HtmlWebpackPlugin({
            template: path.resolve('./', 'index.html'),
            webpackDevServer: '/webpack-dev-server.js'
        })
    ]
};

module.exports = config;

In case someone has this error on firebase
https://stackoverflow.com/questions/44908044/babel-not-polyfilling-fetch-when-using-babel-preset-env/64791611#64791611
I fixed it like this