webpack dynamic import not working

A curious software developer with a passion for solving problems and learning new things. Ive tried several different variations of the imports. With the above ES proposal the keyword import gets more power and turns also into a function which returns a Promise: The above code will load the foo module at runtime, and resolving it, will log the default export of the module. Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2. dynamic import for chunk in node_modules is not working as expected #10722 alexander-akait mentioned this issue Ability to force bundling of a module #11223 alexander-akait closed this as completed on Jul 24, 2020 Sign up for free to join this conversation on GitHub . Use webpackPrefetch: true magic comment with webpackChunkName . This argument calls a dynamic import and returns a promise. To do so, we can simply use, instead of webpackMode: eager the webpackPrefetch: true which makes the browser download the chunks after the parent bundle/chunk. We will see what is meant by that in the following sections, where we will examine the customizations the import function can accept. import() work. Although it worked with webpack@3. Keep in mind that you will still probably need babel for other ES6+ features. If you find this article helpful, please share it with others ? So, to make it work with webpack you need to first install the babel-plugin-syntax-dynamic-import . The most valuable placeholders are [name], [contenthash], and . webpack version: 4.25.1 If you are using Webpack 4.0, code splitting requires minimal configuration, Here, the return import construct is used for modules which need to be loaded dynamically. After building your project with that code you will discover that webpack created distinct async chunks for every module in the utilities directory. If dependencies are not provided, factoryMethod is called with require, exports and module (for compatibility!). Dynamically load modules. Aside from the module syntaxes described above, webpack also allows a few custom, webpack-specific methods: Specify a whole group of dependencies using a path to the directory, an option to includeSubdirs, a filter for more fine grained control of the modules included, and a mode to define the way how loading will work. Recovering from a blunder I made while emailing a professor. Create A New Project # How do I remove a property from a JavaScript object? @sokra @evilebottnawi Any updates on this issue? But I'm not being able to dynamically load external libraries from variables. Node.js version: v14.4.0 Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. By adding comments to the import, we can do things such as name our chunk or select different modes. Is it possible to make webpack search this file from node_modules? If youre using HTTPS is even worse! I have been following the SO questions and implemented something similar to this answer in a React + Webpack project. The keyword here is statically. Additional tools: The text was updated successfully, but these errors were encountered: Please create minimum reproducible test repo. Throughout the article we will be using live examples(all of them in the form of a StackBlitz app) and diagrams, so let's get started! As imports are transformed to require.ensure there are no more magic comments. Thanks T. I guess I cannot 'dynamically' load/include only the component I need on a pre page basis, I'll have to manually include all available componests so if they are within the 'layout' object, then they will be available. How can I remove a specific item from an array in JavaScript? // Here the user chooses the name of the module. However, if you try with any other module than cat, the same error will appear: This feature could be used to enforce modules to be loaded beforehand, so that you ensure that at a certain point the modules accessible. Connect and share knowledge within a single location that is structured and easy to search. Find centralized, trusted content and collaborate around the technologies you use most. In this article we will learn about demistifying webpack's 'import' function: using dynamic arguments. The ES2015 Loader spec defines import() as method to load ES2015 modules dynamically on runtime. Whats the grammar of "For those whose stories they are"? I've read everything I can find in the webpack documentation and every relevant link Google produces for two days with no luck. This will cache the Files on Browser and avoid problems related to Chunks not found (Chunk loading failed) with multiple deploys. All the following sections will be based on the same example where there is a directory called animals and inside there are files that correspond to animals: Each examples uses the import function like this: import('./animals/${fileName}.js'). You put it in like so: "syntax-dynamic-import". The problem is if you want to dynamically load a file, in this case, an image, Webpack by default generate a chunk for that module, something similar to this: The big issue with that is when you request dynamic imported images, it will do a network request to get the chunk and then another one to get the image, adding unnecessary overhead to your app. Where does this (supposedly) Gibson quote come from? Using it in an async function may not have the expected effect. or on Twitter at @heypankaj_ and/or @time2hack. While webpack supports multiple module syntaxes, we recommend following a single syntax for consistency and to avoid odd behaviors/bugs. // And here the chunk is loaded. For example, with core-js@3: webpack.config.js const config = { entry: [ The way we're currently doing things, the cat module is not loaded from anywhere else, so this is why we're facing an error. The text was updated successfully, but these errors were encountered: You could use webpackIgnore comment if you want to use import to load an external file: This directive comment prevents webpack from parsing the import expression. Since webpack 2.6.0, the placeholders [index] and [request] are supported within the given string to an incremented number or the actual resolved filename respectively. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. The other modules whose values are null are called orphan modules. This feature relies on Promise internally. // similarly to other require/import methods. Asking for help, clarification, or responding to other answers. It is crucial to have a (root) parent chunk because it contains the required logic to fetch and integrate other child chunks in the application. It takes all of the code from your application and makes it usable in a web browser. Now here's the part that errors on build. It's totally understandable that webpack is a bundler and it should not take care of loading script from another domain. The First line of the Readme of the repo: And this is what is causing all the trouble. The [contenthash] substitution will add a unique hash based on the content of an asset. Which you can see here: GitHub - airbnb/babel-plugin-dynamic-import-webpack: Babel plugin to transpile import() to require.ensure, for Webpack. He suggested me to use the public folder as described in the create-react-app readme and to not import the SVGs via webpack: */ by default(you can think of it as a glob pattern). In this case, having only a responsive design doesnt cover what you want, so you build a page renderer which loads and renders the page based on the user platform. https://github.com/roblan/webpack-external-promise-import, __webpack_require__ should not be called on promise external result. Using it asynchronously may not have the expected effect. Does a summoned creature play immediately after being summoned by a ready action? That's because the chunk will be served from a cache internally maintained by webpack and the required module will be retrieved from the array/object of modules where webpack records them. The goal of CommonJS is to specify an ecosystem for JavaScript outside the browser. Check out the guide for more information on how webpackPreload works. To learn more, see our tips on writing great answers. What webpack does in this case is to keep track of whether modules that match the import's expression exist or not and also keep track of modules' exports type, if needed(e.g if they are all ES modules, then there is no need for it). // Do something with lodash (a.k.a '_') // imagine we had a method to get language from cookies or other storage, /* webpackExports: ["default", "named"] */, /* webpackExclude: /\.noimport\.json$/ */, // in theory; in praxis this causes a stack overflow, /* optional, default /^\.\/. Finally I fixed this by setting __webpack_public_path__ webpack setting. provide a real example: Webpack Dynamic Import Expression Not Working, Adding asssets outside of the module system, https://github.com/webpack/webpack/issues/5747, How Intuit democratizes AI development across teams through reusability. But as Uncle Ben once said: Know how the tool works in essential to use its maximum performance, and I hope I helped you to know a little more about it now! // Dynamically loading the `cat.js` module. require(imageUrl) // doesn't work This is because it doesn't know the path at compile time if the path is stored in a variable. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. You might be wondering now: isn't it a waste of resources, if webpack creates multiple chunks when in the end there will be only one chunk that matches the path? Using fetch I could load the images dynamically from the public folder and start webpack without getting ever again a memory issue. If the current behavior is a bug, please provide the steps to reproduce. ? The value here can be anything except a function. Built at: 02/04/2019 6:39:47 AM @ooflorent Is it possible to import the bundle from external url in webpack for e.g. Then I came across a comment in one of the web packs repo: After struggling for a few minutes and a few trials and errors, I realized that I dont need to configure comments in babel configuration. Operating System: MacOS 10.15.6 I cant thank you enough maksim! Version 2 of webpack supports ES6 module syntax natively, meaning you can use import and export without a tool like babel to handle this for you. But Webpack can detect files to bundle when it is given a string interpolation in require() like: This is wrapped in a JavaScript object and executed using node VM. 7 comments LASkuma commented on Nov 5, 2018 edited webpack-bot added the inactive label on May 31, 2019 alexander-akait closed this as completed on May 31, 2019 colscott mentioned this issue on Jun 16, 2019 Ive setup my code according to the jet-demos example and still not having any luck with webpack generating the chunk file. Basically, 9 indicates a simple ES module, case in which the module with the moduleId will be required. For example, import(`./locale/${language}.json`) will cause every .json file in the ./locale directory to be bundled into the new chunk. Use require instead, e.g. In the multi-page development phase, the project starts with a small number of pages, the compilation speed is tolerable, but once the page increases, the multiple hot updates cause memory overflow. Learn 5 Optimization Tips for Webpack Step by Step Somnath Singh in JavaScript in Plain English Coding Won't Exist In 5 Years. So the role of the map object from above is so keep track of modules which have a purpose(i.e if they are used at all) at all in the project. import('http://example.com/some-module/some-module.bundle.js').then(module => console.log(module.default)); How can I load an external resource from an external url? Similar to require.ensure, this will split the given dependencies into a separate bundle that will be loaded asynchronously. When using CommonJS module syntax, this is the only way to dynamically load dependencies. ), Yeah there really seems something wrong here. Get the latest coverage of advanced web development straight into your inbox. As a smart developer, you dont want to load the entire code for desktop if the user is on mobile, and vice versa. Find centralized, trusted content and collaborate around the technologies you use most. Angular implements two strategies to control change detection behavior on the level of individual components. reactjs ComponentA myComponents ComponentA adsbygoogl I don't know if there's a cleaner way, but I've seen script.js used with success for the google maps api specifically. You do not need to add curly brackets. An in-depth perspective on webpack's bundling process, Change detection and component trees in Angular applications, Improve page performance and LCP with NgOptimizedImage, Deep dive into the OnPush change detection strategy in Angular, Deep dive into the infamous ExpressionChangedAfterItHasBeenCheckedError inAngular, From zone.js to zoneless Angular and back how it all works. A prefetched chunk can be used anytime in the future. Thanks for contributing an answer to Stack Overflow! Here's my test repository https://github.com/younabobo/webpack-dynamic-import-test, @younabobo @evilebottnawi The compiler will ensure that the dependency is available in the output bundle. Any help would be greatly appreciated. According to the document: I should upload dist files of my-custom-comp to cdn or copy dist files of my-custom-comp to app's assets folder? However, there's likely a reasonable amount of optimization that can still be done. What is the expected behavior? Can you write oxidation states with negative Roman numerals? You can also subscribe to our weekly newsletter at http://frontendweekly.co, import(`assets/images/${imageName}.jpg`).then( src => ), is better to break the big bundles in smaller pieces. Similar one works for me ( not exactly the same version of Webpack though ), Try to add one more comment to force code splitting. https://webpack.js.org/guides/code-splitting/#dynamic-imports, https://babeljs.io/docs/plugins/syntax-dynamic-import/#installation. It's possible to dynamically import relative modules: const LazyComponent = lazy(() => import('/folder/${fileVariable}'))``. Hey, I noticed that Webpack just put numbers to generated chunks. Would anyone have any ideas as to why webpack wouldnt create the chunk files? Lets refactor our function: - Still not good! If this function returns a value, this value is exported by the module. @ufon @younabobo Maybe you can provide reproducible test repo too? Not the answer you're looking for? Note that webpackInclude and webpackExclude options do not interfere with the prefix. Already on GitHub? Dynamic imports syntax is recently introduced in the language and hence is not a standard yet. Webpack 3, Dynamic Imports, Code Splitting, and Long Term Caching Made Easy. Old solution A solution is to use node --max_old_space_size=8000 scripts/start.js to get it working. React.lazy handles this promise and expects it to return a module that contains a default export React component. @sokra Could you be more specific? So now I am using this fetch library, which was already included in the config (generated by create-react-app after ejecting) This is because webpack can't know during the compilation what modules will be imported. Babel plugin to transpile import () to require.ensure, for Webpack. // Here the chunk that depends on `fileName` is loaded. Why are Suriname, Belize, and Guinea-Bissau classified as "Small Island Developing States"? This way, all the file paths will be promptly available when your app loads the parent bundle/chunk. - A preloaded chunk should be instantly requested by the parent chunk. fish.js Using Webpack and the dynamic import structure it creates a promise that will retrieve the chunk at runtime and allow you to act on it at that point. Inline comments to make features work. [6] ./sources/views/admin/win_create_subsuser.js 3.24 KiB {0} [built] Now if we want to use the lion module, I should not see a new request, but only a confirmation that the lion module has been executed: Here's a diagram to supplement what's been accumulated so far: We've saved this section until last because of its peculiarities. The upside of this way of loading modules is that you don't overload the main chunk with all the possible modules that can match the import's expression, but rather they are put in another chunk which can be loaded lazily. Have set up very simple tester with following packages: and my page I want to load dynamically with separate bundle. Webpack begins code splitting our application as soon as it encounters this syntax. How do I return the response from an asynchronous call? require.ensure([], function(request) { request('someModule'); }) isn't handled by webpack's static parser. That's why I get the following exception: How can I dynamically import all SVGs using webpack, without getting a heap out of memory error? Configuring webpack can be tricky when there are so many things going on. The traversal starts from the first static part of the provided path(in this case it is ./animals) and in each step it will read the files from the current directory and will test the RegExp object against them. Thereby I am using webpacks dynamic import syntax like so import('../images_svg/' + svgData.path + '.svg') sadly this doesn't work. Have a question about this project? Hopefully, at this point, things make more sense when it comes to using import with dynamic arguments. How to get dynamic imports to work in webpack 4, How Intuit democratizes AI development across teams through reusability. to your account, What is the current behavior? This implies that the resources in question should by now be loaded(i.e required and used) from somewhere else, so as to when a weak import is used, this action doesn't trigger any fetching mechanisms(e.g making a network request in order to load a chunk), but only uses the module from the data structure that webpack uses to keep track of modules. This can be verified in our example: after starting the server, try to require any of the modules present in the animals directory. Subscribe to the blog to receive new posts right to your inbox. I'm trying to migrate my app to webpack 4. Because foo could potentially be any path to any file in your system or project. This makes debugging harder, as I dont know if one specific chunk was loaded or not!. By clicking Sign up for GitHub, you agree to our terms of service and Webpack and Dynamic Imports: Doing it Right | by Rubens Pinheiro Gonalves Cavalcante | Frontend Weekly | Medium 500 Apologies, but something went wrong on our end. webpack generated code (added line breaks for clarity): part .then((m) => __webpack_require__.t(m, 7)) seems to be unnecessary. How to check whether a string contains a substring in JavaScript? Thanks for contributing an answer to Stack Overflow! Although it is a popular selling point of webpack, the import function has many hidden details and features that many developers may not be aware of. Dynamic import seems to be the solution but I'm not having any luck getting webpack to create the chunk files. At run time, when the variable language has been computed, any file like english.json or german.json will be available for consumption. For now, we will focus on the import's argument. It allows code to render synchronously on both the server and initial page-loads on the client. And consider adding service workers with a good caching strategy. To recap: Webpack's placeholders allow you to shape filenames and enable you to include hashes to them. { type:"header", template:"Dynamically imported UI" }. Using docker volume properly will lead to higher productivity. For instance, the import function can accept dynamic expression and still be able to achieve well known features such as lazy loading. In this article we've learned that the import function can do much more than simply creating a chunk. Then, if you open the dist/main.js file, you can already notice the map we talked about earlier: Once again, this object follows this pattern: { filename: [moduleId, chunkId] }. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. webpack.config.js. This CANNOT be used in an async function. If you type cat in the input and then press the button, you'll notice an error in the console: And this should make sense because, as it's been mentioned previously, the weak import expects that the resource should already be ready to be used, not to make webpack take action in order to make it available. For some reason, I could not identify the Chunks by name as they were pretty random as 1234.asdfd23534kjh346mn63m46.chunk.js, So to resolve this, I updated the chunkName in output of webpack config to [name]. If you think this is still a valid issue, please file a new issue with additional information. True, even if were dynamic loading the components, this stills a pretty attached solution. // Requesting the module that should already be available. [41] ./sources/locales sync ^\.\/.$ 181 bytes {0} [built] Theoretically Correct vs Practical Notation, How do you get out of a corner when plotting yourself into a corner, How to handle a hobby that makes income in US, Replacing broken pins/legs on a DIP IC package, Surly Straggler vs. other types of steel frames. By clicking Sign up for GitHub, you agree to our terms of service and It's also worth exploring a case where the array has the module's exports type specified. You put it in like so: "syntax-dynamic-import". Let's take a deep dive into docker volume & its configuration options. Otherwise, an error will be thrown. How do I include a JavaScript file in another JavaScript file? This button displays the currently selected search type. In order to quickly mitigate this issue, we can add an import * as c from './animals/cat'; statement at the beginning of the file: If we run npm run build and npm run start again and take the same steps, we should see that the cat module has been successfully executed. [38] ./sources/styles/anytime.css 39 bytes {0} [built] [4] ./sources/views/admin/win_create_subscription.js 5.75 KiB {0} [built] Entrypoint anytime = anytime.css anytime.bundle.js Webpack: Common chunks for code shared between Webworker and Web code? Now it works. Currently, @babel/preset-env is unaware that using import() with Webpack relies on Promise internally. This Is Why fatfish in JavaScript in Plain English It's 2022, Please Don't Just Use "console.log" Anymore Jesse Langford in Better Programming Consolidate Your TypeScript Imports With index.ts Files Help Status Writers Blog How do I check if an element is hidden in jQuery? Special thanks Max Koretskyi for reviewing this article and for providing extremely valuable feedback. privacy statement. ? As with the static import situation where the path is known at compile time(e.g import('./animals/cat.js)), when only one chunk would be created, when the import's path is dynamic, the loaded chunk will be cached, so no important resources will be wasted in case the same chunk is required multiple times. It's really hard to keep up with all the front-end development news out there. Connect and share knowledge within a single location that is structured and easy to search. My head hurts already. This concept of a map which is used to keep track of modules and their traits is used regardless of the mode we're using. webpackPreload: Tells the browser that the resource might be needed during the current navigation. There is also an article named An in-depth perspective on webpack's bundling process in which concepts such as Modules and Chunks are explained, but it shouldn't affect the understanding of this article too much. // In this example, the page shows an `input` tag and a button. webpackMode: Since webpack 2.6.0, different modes for resolving dynamic imports can be specified. But I can't get it to work. My problem was closely related to #7417, @younabobo It is documented, we can't build module from x, it is runtime value and it is impossible to detect https://webpack.js.org/api/module-methods/#dynamic-expressions-in-import, @ufon You need this #11127, we will implement it for webpack@5. Technically, you could stop here and officially have done code splitting! The nature of simulating nature: A Q&A with IBM Quantum researcher Dr. Jamie We've added a "Necessary cookies only" option to the cookie consent popup. [1] ./sources/globals.js 611 bytes {0} [built] [8] ./sources/views/timeclock/win_userdepts.js 3.39 KiB {0} [built] Is it possible to rotate a window 90 degrees if it has the same length and width? Lazy Loading is a hot topic for the optimization of web applications. Already have an account? Is it suspicious or odd to stand by the gate of a GA airport watching the planes? It is very useful for lazy-loading. Underlying modules can then be easily resolved later on: If mode is set to 'lazy', the underlying modules will be loaded asynchronously: The full list of available modes and their behavior is described in import() documentation. Any module that matches will not be bundled. *\\.js$/ and it will be tested against all the files which reside in the animals/ directory(e.g regExp.test('./cat.js')). [0] ./node_modules/css-loader!./node_modules/less-loader/dist/cjs.js!./sources/styles/anytime.css 1.18 KiB {0} [built] [40] ./sources/views sync ^\.\/.$ 1.62 KiB {0} [optional] [built] The require label can occur before a string. Therefore a cache in the runtime exists. // the chunk whose name corresponds to the animal name will be loaded. I was trying to optimize the React App and as we already have splitChunks in our webpack configuration, it was for granted to pay more attention to code splitting. Thus, there are 3 filters that a module must overcome: it must match with the imports expression, it must be used across the app(e.g it is directly imported or imported through a chunk) and it must be available(i.e already loaded from somewhere else). | by Geoff Miller | CloudBoost Write Sign up Sign In 500 Apologies, but something went wrong on our end. This will export the provided value. As the import is a function receiving a string, we can do powerful things like loading modules using expressions. I can build the jet-demos project files and the bundle files are created in /codebase/. cat.js This will result in the following output: Without require.include('a') it would be duplicated in both anonymous chunks. Although the articles use React and React+Redux on the examples, you can apply the same very idea in any SPA based framework/library: Code splitting is a powerful thing to make your application faster, smartly loading the dependencies on the run. Please pay attention to these enforcements before you read on: Version 2 of webpack supports ES6 module syntax natively, meaning you can use import and export without a tool like babel to handle this for you. I've tried with a couple of magic comments from webpack like the example below, but nothing worked so far: const LazyComponent = lazy(() => import(/* webpackIgnore: true */ packageOne)), Hi @Miaoxingren, curious how were you able to fix this issue? How to use Slater Type Orbitals as a basis functions in matrix method correctly? Pablo Montenegro 38 Followers https://pablo.gg Follow More from Medium Gejiufelix in Lets check it on the code below: But hey, this is a pretty simplist approach. By default webpack import all files from views folder, which can conflict with code splitting.

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