Writing embeddable Javascript plugin with React & Webpack - javascript

I want to be able to bundle my React app with Webpack such that distributed copies put onto a CDN can be sourced, called and initialised with a bunch of config relevant to a client.
After reading this and this, I'm setting up my webpack entry file as follows:
// ... React requires etc.
(() => {
this.MyApp = (config) => {
// some constructor code here
}
MyApp.prototype.init = () => {
ReactDOM.render(<MyReactApp config={MyApp.config} />, someSelector);
}
})();
The idea being that in my client, I can do something like the following:
<script src="./bundle.js" type="text/javascript"></script>
<script type="text/javascript">
MyApp.init({
some: "config"
});
</script>
And my MyApp#init function will render my React app inside some container on the client.
Am I thinking about this in the right way? Is there a simpler or more efficient way to go about this?
My error is Uncaught TypeError: Cannot set property 'MyApp' of undefined, since this inside the IIFE is undefined. I'd really like to understand both why this is happening and advice on how to fix it.
Thanks in advance!

So I kind of found a solution to this, as described here
If I change my webpack.config.js file to add the following attributes to the output object, i.e.
var config = {
// ...
output: {
// ...
library: 'MyApp',
libraryTarget: 'umd',
umdNamedDefine: true,
}
}
This specifies the file I'm bundling with webpack as a UMD module, so if I have a function in that file and export it...
export const init = (config) => {
ReactDOM.render(<MyReactApp config={config} />, someSelector);
}
I can then, in my client, do the following.
<script src="./bundle.js" type="text/javascript"></script>
<script type="text/javascript">
MyApp.init({
some: "config"
});
</script>
And my React app renders.
If anyone thinks this is a daft way of doing it, I'd love to hear it!
MORE INFORMATION ON WEBPACK CONFIG
Please bear in mind I haven't touched this code in a while. Given it's Javascript, the world has likely moved on and some practises may be outdated.
This is my React entrypoint file (src/index.js)
import 'babel-polyfill';
import React from 'react';
import { render } from 'react-dom';
import Root from './components/Root';
import configureStore from './lib/configureStore';
const store = configureStore();
export const init = (config) => {
render(
<Root store={store} config={config} />,
document.querySelector(config.selector || "")
);
}
This is my Webpack config (webpack.config.js)
var webpack = require('webpack');
var path = require('path');
var loaders = require('./webpack.loaders');
module.exports = {
entry: [
'webpack-dev-server/client?http://0.0.0.0:8080', // WebpackDevServer host and port
'webpack/hot/only-dev-server',
'./src/index.js' // Your appʼs entry point
],
devtool: process.env.WEBPACK_DEVTOOL || 'source-map',
output: {
path: path.join(__dirname, 'public'),
filename: 'bundle.js',
library: 'Foo',
libraryTarget: 'umd',
umdNamedDefine: true,
},
resolve: {
extensions: ['', '.js', '.jsx']
},
module: {
loaders: loaders
},
devServer: {
contentBase: "./public",
noInfo: true, // --no-info option
hot: true,
inline: true
},
plugins: [
new webpack.NoErrorsPlugin()
]
};
As you can see, my Webpack config outputs my bundle.js which is what my front-end will ingest.

You have enclosure around your class.
MyApp needs to be exported or attached to the global window object before you can call it like that.
In your situation you are actually not calling MyApp.init() but you are calling window.MyApp.init(), but global object window does not have object MyApp attached to it.
// ... Simple attaching MyApp to the window (as a function)
window.MyApp = (config) => {
...
}
// ... Using class and export
class MyApp {
constructor(config){...}
}
export default MyApp
// or simply attach to the window
window.MyApp = MyApp
I would prefer to create class and export module using export. Then create another file just for attaching to the window. Since it is not considered best practice to attach classes to the window like that.
// Import module and attach it to the window
import MyApp from '.my-app'
window.MyApp = MyApp
You can look for advanced options of exporting modules as UMD, AMD...

Related

Cypress: import modules via alias

in my project i am using cypress with plain javascript. i am facing the challenge of importing the modules (page objects) via aliases instead of spaghetti code like ../../../../folder/page.js.
I don't use typescript or react.js and don't have a src folder/directory.
my tests run locally in the browser or via a docker image (pipeline).
I would like to transform from this:
import { LoginPage } from "../../pages/loginPage.js";
to something like this:
import { LoginPage } from "#Pages/loginPage.js";
but I always get an error:
Error: Webpack Compilation Error
./cypress/e2e/accountOverview/accountOverviewPageTest.spec.js
Module not found: Error: Can't resolve 'Pages/loginPage.js' in 'C:\Users\User\automated_frontend_tests\automated_frontend_tests\cypress\e2e\accountOverview'
resolve 'Pages/loginPage.js' in 'C:\Users\User\automated_frontend_tests\automated_frontend_tests\cypress\e2e\accountOverview'
Parsed request is a module
using description file: C:\Users\User\automated_frontend_tests\automated_frontend_tests\package.json (relative path: ./cypress/e2e/accountOverview)
Field 'browser' doesn't contain a valid alias configuration
Looked for and couldn't find the file at the following paths:
[C:\Users\User\automated_frontend_tests\automated_frontend_tests\cypress\e2e\accountOverview\node_modules]
[C:\Users\User\automated_frontend_tests\automated_frontend_tests\cypress\e2e\node_modules]
[C:\Users\User\automated_frontend_tests\automated_frontend_tests\cypress\node_modules]
[C:\Users\node_modules]
[C:\node_modules]
[C:\Users\User\automated_frontend_tests\automated_frontend_tests\node_modules\Pages\loginPage.js]
[C:\Users\User\automated_frontend_tests\node_modules\Pages\loginPage.js]
[C:\Users\User\node_modules\Pages\loginPage.js]
[C:\Users\User\automated_frontend_tests\automated_frontend_tests\node_modules\Pages\loginPage.js.js]
[C:\Users\User\automated_frontend_tests\node_modules\Pages\loginPage.js.js]
[C:\Users\User\node_modules\Pages\loginPage.js.js]
[C:\Users\User\automated_frontend_tests\automated_frontend_tests\node_modules\Pages\loginPage.js.json]
[C:\Users\User\automated_frontend_tests\node_modules\Pages\loginPage.js.json]
[C:\Users\User\node_modules\Pages\loginPage.js.json]
[C:\Users\User\automated_frontend_tests\automated_frontend_tests\node_modules\Pages\loginPage.js.jsx]
[C:\Users\User\automated_frontend_tests\node_modules\Pages\loginPage.js.jsx]
[C:\Users\User\node_modules\Pages\loginPage.js.jsx]
[C:\Users\User\automated_frontend_tests\automated_frontend_tests\node_modules\Pages\loginPage.js.mjs]
[C:\Users\User\automated_frontend_tests\node_modules\Pages\loginPage.js.mjs]
[C:\Users\User\node_modules\Pages\loginPage.js.mjs]
[C:\Users\User\automated_frontend_tests\automated_frontend_tests\node_modules\Pages\loginPage.js.coffee]
[C:\Users\User\automated_frontend_tests\node_modules\Pages\loginPage.js.coffee]
[C:\Users\User\node_modules\Pages\loginPage.js.coffee]
# ./cypress/e2e/accountOverview/accountOverviewPageTest.spec.js 5:17-46
I have tried several solutions, including:
//webpack.config.js
module.exports = {
resolve: {
alias: {
"#pages": path.resolve(__dirname, "cypress/pages/*"),
},
},
};
//testspec file
import { LoginPage } from "#pages/loginPage.js";
const loginPage = new LoginPage();
#Uzair Khan:
I tried your solution, but it still didn't work. The error message remains the same. It seems that the IDE does not search in the correct folder, but only in ...\node_modules\#page\loginPage.js which makes no sense.
If I enter const loginPage = new LoginPage(), the module LoginPage() cannot be found by the IDE either. Something is wrong with the solution. Do I still have to install any packages via NPM?
In your webpack.config.js file add resolve.alias which you want to make alias. It looks like something this below:
resolve: {
alias: {
'#page': path.resolve(__dirname, '{path you want to make alias}')
}
}
Since you are using cypress, you have to update the resolve path in cypress.config.js. Here is mine cypress.config.js
import { defineConfig } from 'cypress'
import webpack from '#cypress/webpack-preprocessor'
import preprocessor from '#badeball/cypress-cucumber-preprocessor'
import path from 'path'
export async function setupNodeEvents (on, config) {
// This is required for the preprocessor to be able to generate JSON reports after each run, and more,
await preprocessor.addCucumberPreprocessorPlugin(on, config)
on(
'file:preprocessor',
webpack({
webpackOptions: {
resolve: {
extensions: ['.ts', '.js', '.mjs'],
alias: {
'#page': path.resolve('cypress/support/pages/')
}
},
module: {
rules: [
{
test: /\.feature$/,
use: [
{
loader: '#badeball/cypress-cucumber-preprocessor/webpack',
options: config
}
]
}
]
}
}
})
)
// Make sure to return the config object as it might have been modified by the plugin.
return config
}
And import in other file via that alias you set in cypress.config.js. Here is mine for example:
import page from '#page/visit.js'
const visit = new page()
When('I visit duckduckgo.com', () => {
visit.page()
})
I think both answers are nearly there, this is what I have for src files:
const webpack = require('#cypress/webpack-preprocessor')
...
module.exports = defineConfig({
...
e2e: {
setupNodeEvents(on, config) {
...
// #src alias
const options = {
webpackOptions: {
resolve: {
alias: {
'#src': path.resolve(__dirname, './src')
},
},
},
watchOptions: {},
}
on('file:preprocessor', webpack(options))
...
path.resolve() resolves a relative path into an absolute one, so you need to start the 2nd param with ./ or ../.
Also, don't use wildcard * in the path, you just need a single folder that will be substituted for the alias in the import statement.
If in doubt, check the folder returned (in the terminal)
module.exports = defineConfig({
...
e2e: {
setupNodeEvents(on, config) {
const pagesFolder = path.resolve(__dirname, './cypress/pages')
console.log('pagesFolder', pagesFolder)

How can I access my javascript after webpack?

I have experience in Javascript and jQuery, but I am new to webpack.
I have a file called test1.js:
exports.func1 = function() {
window.alert('hello from func 1');
};
I then have index.js, which contains the following:
import test1 from "./test1"
My webpack.config.js contains:
const path = require('path');
module.exports = {
entry: './index.js',
output: {
filename: 'app.js',
path: path.resolve(__dirname, 'dist'), //folder to put the output file
},
};
I have included app.js into my webpage and that is fine, no errors in console about file cannot be found. I want to call func1() from a button click, for example, <button onclick="func1()">Test</button>.
When I do this I get "func1 is not defined" in console output. Webpack doesn't show any errors when I run it, so it must be the way I am calling the function somehow.
I must be doing something, or not doing something, really stupid. Can someone help as I seem to be going round in circles? Thanks.
It's because test1 is the exported object. func1 is a property of test1.
test1.func1() will invoke the function
You could also import it by destructuring. Try the following:
import { func1 } from './test1'
Change test1.js to:
export default () => {
window.alert('hello from func 1');
};
Then in your index.js:
export { default as test1 } from "./test1"
If you want to consume in HTML you should build a library and update your webpack like below:
const path = require('path');
module.exports = {
entry: './index.js',
output: {
filename: 'app.js',
path: path.resolve(__dirname, 'dist'), //folder to put the output file
library: 'myApp',
libraryTarget: 'umd',
},
};
Now your function is exported and should be available for usage.

Webpack 4, how to import a module into another module that are both entry points?

I'm new to Webpack, so my terms may not be entirely correct. What I'm trying to do is build a custom Phaser module first, then import it into the other entry point, which depends on it.
EDIT: I've tried using SplitChunks, Dynamic Imports, and aliases. But no avail. Is there anyway to accomplish this via plugins or methodology?
From webpack.config.js:
entry: {
'phaser.min': './phaser-builder.js',
game: './src/index.js'
},
resolve: {
alias: {
'eventemitter3': path.resolve(__dirname, './node_modules/eventemitter3')
},
modules: [ 'node_modules/phaser/src', 'node_modules' ]
},
output: {
path: path.resolve(__dirname, 'build'),
filename: '[name].js',
library: 'Phaser',
libraryTarget: 'umd',
sourceMapFilename: '[file].map',
devtoolModuleFilenameTemplate: 'webpack:///[resource-path]',
devtoolFallbackModuleFilenameTemplate: 'webpack:///[resource-path]?[hash]',
umdNamedDefine: true
},
Contents of phaser-builder.js:
require('polyfills');
var CONST = require('const');
var Extend = require('utils/object/Extend');
var Phaser = {
... code ...
};
Phaser = Extend(false, Phaser, CONST);
module.exports = Phaser;
global.Phaser = Phaser;
index.js (second entry point) needs the 'Phaser' object from phaser.min.js that is created from ./phaser-builder.js (first entry point) as shown below:
Contents of index.js:
//import 'phaser'; //this works but it's not the custom build from entry point one.
import { Phaser } from '../build/phaser.min';
import { TestScene } from './scenes/TestScene';
const gameConfig = {
width: 680,
height: 400,
scene: TestScene
};
new Phaser.Game(gameConfig);
Contents of TestScene.js: (imported in index.js)
export class TestScene extends Phaser.Scene {
preload() {
this.load.image('logo', 'assets/sprites/logo.png');
}
create() {
this.add.text(100, 100, 'Working...', { fill: '#0f0' });
this.add.image(100, 200, 'logo');
}
}
As commented in index.js above, if I simply use import 'phaser'; (which is pulling from node_modules I presume?) Everything works fine. But that is the full phaser lib, which I don't want. I want to import the custom build I created in entry point one, that exists in /build/phaser.min.js
If I try importing from /build/phaser.min.js I get this error:
"TypeError: Super expression must either be null or a function"
Which from my understanding is basically saying that Phaser object/module is undefined, so TestScene is not extending Phaser.Scene as expected.
With webpack I add specific build of phaser in the followed way, I hope this is what you are looking for or at least will give you any idea how could we do with webpack
thank you.

How to properly export an ES6 module function as a library for use in a node app?

Let's say that I have a node.js application, which does NOT go through my webpack bundling:
Node App
const Html = require('./build/ssr-bundle.js');
let result = Html.ssrbundle.render();
console.log(result);
Here is my ES6/JSX file, which is getting processed by webpack and I want to be able to access that render function in my node app (you guessed right, I am trying to SSR react stuff ;) )
src/Html.js -(webpack)-> build/ssr-bundle.js
import React from 'react';
import ReactDOMServer from 'react-dom/server';
import CustomComponent from './custom-component.js';
module.exports = {
render : function () {
return ReactDOMServer.renderToString(<CustomComponent />);
} };
And here is my Webpack config
webpack.config.js
var path = require('path');
module.exports = {
entry: {
ssr: './src/Html.js',
//frontend: './src/frontend-Html.js'
},
output: {
path: path.resolve(__dirname, 'build'),
filename: 'ssr-bundle.js',
library: 'ssrbundle'
},
module: {
rules: [
{
test: /\.js$/,
loader: 'babel-loader',
query: {
presets: ['env','react'],
plugins: ["transform-es2015-destructuring", "transform-object-rest-spread"]
}
},
{
test:/\.css$/,
use:['style-loader','css-loader']
}
]
},
stats: {
colors: true
},
devtool: 'source-map'
};
Whatever I do, I cannot figure out how to properly use that exported variable "ssrbundle" and subsequently the render function. If I had my node app included in the bundle, everything would be all right, but this is not what I want to do.
As apokryfos suggested, I played around with the libraryTarget Webpack setting. You can find more info on using Webpack to author a library (what I was really trying to achieve) here:
https://webpack.js.org/guides/author-libraries/
and here are code examples:
https://github.com/kalcifer/webpack-library-example/blob/master/webpack.config.babel.js.
What did the trick for me, was to set the libraryTarget to "umd" , which is different than the "var" setting which is set by default and is suitable i.e. for including the script in an HTML file

How do I create a webpack import alias in React Static Boilerplate?

I have the following import:
// cwd: /project/pages/blog/category/red/index.js
import PageHeader from '../../../components/PageHeader';
And I want to be able to write it this way (anywhere in my project):
// cwd: /project/pages/blog/category/red/index.js
import PageHeader from 'components/PageHeader';
I've tried using webpack resolve option but I can't seem to make it work:
config.resolve = {
alias: {
components: [
path.resolve('../components/')
]
}
};
and
config.resolve = {
root: [
path.resolve('../')
]
};
Am I missing something ?
My app architecture is forked from React Static Boilerplate, so my webpack.config.js looks like this one
config.resolve = {
alias: {
components: path.resolve('../components/')
}
};
alias accepts key value pairs, with value being of type string. I am not sure if it works with array.
To answer more specificly it would good to know where PageHeader and your webpack config is:
assuming:
PageHeader is in /project/pages/components
and your webpack config is at the root level /project
then your resolve would look something like this:
config.resolve = {
alias: {
components: path.resolve('./pages/components')
}
};
again it depends on the path to your webpack config and your components directory. The path.resolve will change corresponding to that.
The problem seems related to React Static Boilerplate, more specifically when the building the static pages.
I found a workaround that does the job for now. I had to prepend a ~ to the alias so it doesn't get "treated" as a node_module..
config.resolve = {
alias: {
"~components": path.resolve(__dirname, '../components'),
"~decorators": path.resolve(__dirname, '../core/scripts/decorators'),
"~helpers": path.resolve(__dirname, '../core/scripts/helpers'),
"~i18n": path.resolve(__dirname, '../core/i18n'),
}
};
Usage:
import fetch from '~helpers/fetch';
import header from '~components/header';
More info about this on this Github issue.

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