Managing Jquery Plugin Dependency in Webpack

Managing jQuery plugin dependency in webpack

You've mixed different approaches how to include legacy vendor modules. This is how I'd tackle it:

1. Prefer unminified CommonJS/AMD over `dist`

Most modules link the dist version in the main field of their package.json. While this is useful for most developers, for webpack it is better to alias the src version because this way webpack is able to optimize dependencies better (e.g. when using the DedupePlugin).

// webpack.config.js

module.exports = {
    ...
    resolve: {
        alias: {
            jquery: "jquery/src/jquery"
        }
    }
};

However, in most cases the dist version works just fine as well.

2. Use the `ProvidePlugin` to inject implicit globals

Most legacy modules rely on the presence of specific globals, like jQuery plugins do on $ or jQuery. In this scenario you can configure webpack, to prepend var $ = require("jquery") everytime it encounters the global $ identifier.

var webpack = require("webpack");

    ...
    
    plugins: [
        new webpack.ProvidePlugin({
            $: "jquery",
            jQuery: "jquery"
        })
    ]

3. Use the imports-loader to configure `this`

Some legacy modules rely on this being the window object. This becomes a problem when the module is executed in a CommonJS context where this equals module.exports. In this case you can override this with the imports-loader.

Run npm i imports-loader --save-dev and then

module: {
    loaders: [
        {
            test: /[\/\\]node_modules[\/\\]some-module[\/\\]index\.js$/,
            loader: "imports-loader?this=>window"
        }
    ]
}

The imports-loader can also be used to manually inject variables of all kinds. But most of the time the ProvidePlugin is more useful when it comes to implicit globals.

4. Use the imports-loader to disable AMD

There are modules that support different module styles, like AMD, CommonJS and legacy. However, most of the time they first check for define and then use some quirky code to export properties. In these cases, it could help to force the CommonJS path by setting define = false.

module: {
    loaders: [
        {
            test: /[\/\\]node_modules[\/\\]some-module[\/\\]index\.js$/,
            loader: "imports-loader?define=>false"
        }
    ]
}

5. Use the script-loader (no longer mantained) to globally import scripts

If you don't care about global variables and just want legacy scripts to work, you can also use the script-loader. It executes the module in a global context, just as if you had included them via the <script> tag.

6. Use `noParse` to include large dists

When there is no AMD/CommonJS version of the module and you want to include the dist, you can flag this module as noParse. Then webpack will just include the module without parsing it, which can be used to improve the build time. This means that any feature requiring the AST, like the ProvidePlugin, will not work.

module: {
    noParse: [
        /[\/\\]node_modules[\/\\]angular[\/\\]angular\.js$/
    ]
}

How to import jquery in webpack

So there are few themes in your webpack.config.js, some of which conflict. Just going to list them so I can better understand what I think you are trying to achieve.

Theme 1

You have an entry called vendor that is clearly referencing a minified jQuery library you have presumably downloaded and placed in the directory specified.

Theme 2

You also have an expose-loader that is essential exposing the jquery library from its node_modules probably listed in the dependencies of your package.json.

This makes the jquery in the node_modules available as $ and jQuery in the global scope of the page where your bundle is included.

Theme 3

You also have included the ProvidePlugin with configuration for jQuery.

The ProvidePlugin is supposed to inject dependencies into the scope of your module code, meaning you do not need to have import $ from 'jquery' instead $ and jQuery will already be available in all of your modules.

Conclusion

From what I have gathered I think you're trying to bundle jQuery from the static file at ./src/main/webapp/js/vendor/jquery-3.3.1.min.js in a vendor bundle.

You are then trying to expose the libraries in the vendor bundle to the global scope (jQuery).

Then also have your application code able to import jQuery from what is made available by the vendor bundle in the global scope.

Answer

So if that is what you are doing you need to do the following things.

Firstly, check in your package.json files dependencies for jquery. If its there you want to remove it, there's no need for it if you're going to use your jquery-3.3.1.min.js file instead to provide jQuery to your application.

Secondly, change your test of the expose-loader to trigger when it sees your jquery-3.3.1.min.js file in your entries, not resolve it from the jquery dependency from your node_modules.

This regex pattern should do the trick.

{
  test: /jquery.+\.js$/,
  use: [{
      loader: 'expose-loader',
      options: 'jQuery'
  },{
      loader: 'expose-loader',
      options: '$'
  }]
}

Thirdly, remove the ProvidePlugin if you're going to import the library explicitly with import $ from 'jquery' you do not need it.

Lastly, you need to tell webpack when it sees an import for jquery it can resolve this from window.jQuery in the global scope. You can do this with the externals configuration you already referenced.

externals: {
  jquery: 'jQuery'
}

With all these changes you should end up with a webpack.config.js file that looks like this.

const path = require('path');
const webpack = require('webpack');
const CleanWebpackPlugin = require('clean-webpack-plugin');
const ExtractTextPlugin = require("extract-text-webpack-plugin");
const UglifyJsPlugin = require('uglifyjs-webpack-plugin');
const CompressionPlugin = require("compression-webpack-plugin");

module.exports = {
    entry: {
        vendor: [
            './src/main/webapp/js/vendor/jquery-3.3.1.min.js',
            // './src/main/webapp/js/vendor/fs.js',
            './src/main/webapp/js/vendor/google-adsense.js',
            './src/main/webapp/js/vendor/jquery.menu-aim.min.js',
            './src/main/webapp/js/vendor/jquery.touchSwipe.min.js',
        ],
        app: './src/main/assets/js/desktop/app.js',
        mobile: './src/main/assets/js/mobile/app.js',
        touch: './src/main/assets/js/touch/app.js',
    },
    module: {
        rules: [{
                test: /\.js$/,
                exclude: /(node_modules|bower_components)/,
                use: {
                    loader: 'babel-loader',
                    options: {
                        presets: ['@babel/preset-env']
                    }
                }
            },
            {
                test: /jquery.+\.js$/,
                use: [{
                    loader: 'expose-loader',
                    options: 'jQuery'
                },{
                    loader: 'expose-loader',
                    options: '$'
                }]
            }
        ],
    },
    plugins: [
        // new CleanWebpackPlugin(['src/main/webapp/assets']),
        new webpack.optimize.CommonsChunkPlugin({
            name: 'common' // Specify the common bundle's name.
        }),
        new UglifyJsPlugin({
            test: /\.js$/,
            sourceMap: process.env.NODE_ENV === "development"
        })
    ],
    output: {
        filename: '[name].js',
        path: path.resolve(__dirname, './src/main/webapp/js')
    },
    externals: {
        jquery: 'jQuery'
    }
};

I hope that does not just give you the answer but enough explanation as to where you were going wrong.

Including additional jQuery plugins globally with Webpack 4

I've gone a few rounds with this type of issue and had the most success with the expose-loader. In your webpack config you should set up a section for jQuery using the following expose loader configuration:

{
    test: require.resolve('jquery'),
    use: [{
        loader: 'expose-loader',
        options: 'jQuery'
    }, {
        loader: 'expose-loader',
        options: '$'
    }]
},

There is a similar SO posts here:

How to import jquery in webpack (their regex pattern did not work for me)

Expose jQuery to real Window object with Webpack

Webpack 2 loading, exposing, and bundling jquery and bootstrap

You should be able to find several other articles/posts using this configuration, it is the only one that I have successfully been able to get to work to date.

Also of note, bootstrap 4 seems to also load or do a require on jQuery internally, so if you include an import or require after your jQuery import/require and plugins, it will reinit jQuery and cause your plugins to lose scope.

How to configure and use jQuery with webpack

You can use webpack.ProvidePlugin to resolve the jQuery as a global identifier. When you use ProvidePlugin you dont want to import jQuery into the modules since it would be available as global variable.

something like

plugins: [
    new webpack.ProvidePlugin({
        $: "jquery",
        jQuery: "jquery"
    })
]

Managing Jquery Plugin Dependency in Webpack