webpack dynamic import not working

In the Lib project: Create an entry point file, say index.js, that exports all the custom React components like this: import {Button} from './button'; import {DatePicker} from . Dynamic imports syntax is recently introduced in the language and hence is not a standard yet. A prefetched chunk can be used anytime in the future. I cant figure out what in my setup is failing. See the spec for more information and import() below for dynamic usage. A normal import statement cannot be used dynamically within other logic or contain variables. you can get around this by using that attribute as the src attribute in a script tag. I am trying to setup dynamic svg imports since my app uses many icons and I don't want to impact startup time to load all icons i.e. Webpack is a static module bundler for JavaScript applications. 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. 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/${fileName}.js'). // Do something with lodash (a.k.a '_') // imagine we had a method to get language from cookies or other storage, /* webpackExports: ["default", "named"] */, /* webpackExclude: /\.noimport\.json$/ */, // in theory; in praxis this causes a stack overflow, /* optional, default /^\.\/. Asking for help, clarification, or responding to other answers. import(/* webpackIgnore: true */ "https://maps.googleapis.com/maps/api/js?v=3.exp&signed_in=true&libraries=places&key=" + gkey); webpack version: 5.0.0-beta.22 The goal of CommonJS is to specify an ecosystem for JavaScript outside the browser. Therefore, I think it's definitely a bug. Have a question about this project? The diagrams have been made with Excalidraw. Using docker volume properly will lead to higher productivity. To learn more, see our tips on writing great answers. Well occasionally send you account related emails. /* webpackChunkName: 'animal', webpackMode: 'lazy-once' */, // Here the user types the name of the module, // Here that module is retrieved directly if possible, otherwise, /* webpackChunkName: 'animal', webpackMode: 'weak' */. Any module that matches will not be bundled. How do you use a variable in a regular expression? Real-world apps dont have only one page at all! (In my case google maps api). https://webpack.js.org/guides/code-splitting/#dynamic-imports, https://babeljs.io/docs/plugins/syntax-dynamic-import/#installation. Other relevant information: Here's my test repository https://github.com/younabobo/webpack-dynamic-import-test, @younabobo @evilebottnawi The following methods are supported by webpack: Statically import the exports of another module. [41] ./sources/locales sync ^\.\/.$ 181 bytes {0} [built] You may want to look into output.publicPath to setup to correct URL. Update: If youre using Babel 7.5+ it already includes the dynamic import plugin for you ;). webpack --env.production true, Hash: 40911497abda454cf910 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]. The bundle analyzer was still showing the chunk names similar to 1234.asdfd23534kjh346mn63m46.chunk.js, And to name my chunks I added magic comments similar to following on all dynamic imports in the codebase. If the current behavior is a bug, please provide the steps to reproduce. I have been following the SO questions and implemented something similar to this answer in a React + Webpack project. The interesting thing is that if now the user requires a different module which also belongs to the just loaded chunk, there won't be any additional requests over the network. 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. Refresh the page, check Medium 's site status, or find something interesting to read. The same file structure is assumed: Keep in mind that you will still probably need babel for other ES6+ features. However, this support does not work with dynamic import() Workaround. // the chunk whose name corresponds to the animal name will be loaded. fish.js But for this article, Im going to use the proposed ES2015 dynamic imports supported by Webpack, since the v2, through a babel plugin and the extra specific Webpack features for it. hey @sowinski, because that's an external script, you can't import it and access its contents directly. Once the npm run build is run, the dist directory should have 2 files: main.js, which is the main chunk, and animal.js, which is the chunk in which all the modules corresponding to the files inside the animals/ directory reside. Created and exported a composite function to do the work, which is able to load for any platform we want using expressions, plus we already exposed two loaders, one for desktop and other for mobile. Already on GitHub? We can try to directly require the cat module(without pressing the Load cat chunk first), but we will end up with an error, saying the module is not available: However, if we load the cat chunk first and then require the module, everything should be working fine: The takeaway from this section is that when using the weak mode, it is expected of the resource to be already at hand. The import() must contain at least some information about where the module is located. Refresh the page, check Medium 's site status, or find something interesting to read. To get it start faster we can use webpack's cache-loader. It's what is considered a "weak" dependency. It's really hard to keep up with all the front-end development news out there. If a hash has changed, the client is forced to download the asset again. Successfully merging a pull request may close this issue. Still no luck ?.Magic Comments are not reaching Webpack. It is not possible to use a fully dynamic import statement, such as import(foo). [3] ./sources/models/m_subscriptions.js 2.38 KiB {0} [built] Built at: 02/04/2019 6:39:47 AM // When clicked, the chunk will be loaded and the module that matches with the `fileName`. Adding the following webpack config with extensionAlias to the next.config.js file (see Workaround 1 in this other issue): /** @type {import("next").NextConfig} . 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. It allows code to render synchronously on both the server and initial page-loads on the client. Well occasionally send you account related emails. So as a solution, I removed this plugin dynamic-import-webpack from Babel and Magic Comments take effect in Webpack. privacy statement. webpackChunkName: A name for the new chunk. 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. Removing values from this cache causes new module execution and a new export. While webpack supports multiple module syntaxes, we recommend following a single syntax for consistency and to avoid odd behaviors/bugs. This CANNOT be used in an async function. *$ namespace object:43**. anytime.css 988 bytes 0 [emitted] anytime Have set up very simple tester with following packages: and my page I want to load dynamically with separate bundle. webpack generated code (added line breaks for clarity): part .then((m) => __webpack_require__.t(m, 7)) seems to be unnecessary. If you want to follow along, you can find a StackBlitz demo here(it's safe to run npm run build first). The following options are supported: webpackPrefetch: Tells the browser that the resource is probably needed for some navigation in the future. Actually webpack would enforce the recommendation for .mjs files, .cjs files or .js files when their nearest parent package.json file contains a "type" field with a value of either "module" or "commonjs". Lets refactor our function: - Still not good! cisco gateway of last resort is not set. True, even if were dynamic loading the components, this stills a pretty attached solution. A few examples of dynamic expressions could be: import('./animals/' + 'cat' + '.js'), import('./animals/' + animalName + '.js'), where animalName could be known at runtime or compile time. - A preloaded chunk has medium priority and instantly downloaded. How to resolve dynamic import from node_modules? Does a summoned creature play immediately after being summoned by a ready action? By adding comments to the import, we can do things such as name our chunk or select different modes. The require label can occur before a string. As a side note, the replacement for the dynamic parts and whether nested directories should be traversed can be chosen by us in the config file: So, wrappedContextRecursive specifies whether nested directories should be traversed or not(e.g considering files inside animals/aquatic/ too or not) and with wrappedContextRegExp we can tell webpack what to replace the expression's dynamic parts with. Connect and share knowledge within a single location that is structured and easy to search. For example, with core-js@3: webpack.config.js const config = { entry: [ privacy statement. @Miaoxingren Please create minimum reproducible test repo. Here it would return { default: 42 }, You are right - my expected behavior part is wrong, but either way it does not work (it works fine with static imports though, so it'a bit inconsistent? Therefore, the use of dynamic import is necessary. This can be used for optimizing the position of a module in the output chunks. Using it asynchronously may not have the expected effect. The value here can be anything except a function. 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. So now I am using this fetch library, which was already included in the config (generated by create-react-app after ejecting) By clicking Sign up for GitHub, you agree to our terms of service and I thought of analyzing our bundle with Webpack Bundle Analyzer and seeing how splitChunks has done the splitting. This button displays the currently selected search type. TypeError [ERR_UNKNOWN_FILE_EXTENSION]: Unknown file extension ".ts" for ./webpack.config.ts, Examples of how to get and use webpack logger in loaders and plugins, __webpack_public_path__ (webpack-specific), __webpack_chunk_load__ (webpack-specific), __webpack_get_script_filename__ (webpack-specific), __non_webpack_require__ (webpack-specific), __webpack_exports_info__ (webpack-specific), __webpack_is_included__ (webpack-specific), No CommonJS allowed, for example, you can't use, File extensions are required when importing, e.g, you should use, File extensions are required when importing wasm file. // Here the user chooses the name of the file. // Here the animal name is written by the user. Adding this comment will cause our separate chunk to be named [my-chunk-name].js instead of [id].js. They will just be placed into an object/array of modules and when the button it clicked, it will execute and retrieve that module on the spot, without additional network requests or any other asynchronous operations. 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. This will export the provided value. They are capable of bundling your app and generating your bundle chunks, and especially lazy loading them, so you can load only the one that you need at a given time. You can take a look into the descriptions in more detail here. The First line of the Readme of the repo: And this is what is causing all the trouble. Secure websites are necessary requirements. 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. 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. Note that all options can be combined like so /* webpackMode: "lazy-once", webpackChunkName: "all-i18n-data" */. Now the Chunks have names similar to List.asdfd23534kjh346mn63m46.chunk.js. 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. Sign in The [contenthash] substitution will add a unique hash based on the content of an asset. The example this section is based on can be found here(make sure to also start the server). [7] ./sources/views/admin/win_changerole.js 3.13 KiB {0} [built] Answer above #8341 (comment), feel free to open issue if something not work as expected. Make all exports from the dependency available in the current scope. It basically uses a strategy pattern that chooses which module should be loaded on runtime. Angular implements two strategies to control change detection behavior on the level of individual components. Dynamic import from node_modules is not working, https://github.com/Miaoxingren/webpack-issue-8934, dynamic import for chunk in node_modules is not working as expected, https://github.com/younabobo/webpack-dynamic-import-test, https://webpack.js.org/api/module-methods/#dynamic-expressions-in-import. However, according to MDN and Google Developer Website, dynamic import should support loading scripts from remote source. For instance, the import function can accept dynamic expression and still be able to achieve well known features such as lazy loading. [9] ./sources/views/admin/dashboard.js 1.58 KiB {0} [built] How to get dynamic imports to work in webpack 4, How Intuit democratizes AI development across teams through reusability. Whats the grammar of "For those whose stories they are"? Node.js version: 10.3.0 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. 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. 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. Dynamic import seems to be the solution but Im not having any luck getting webpack to create the chunk files. Available since webpack 5.0.0-beta.18. My head hurts already. But what is the difference between prefetch and preload?. @sokra Could you be more specific? Dynamic Import from external URL will throw, v2 Addon Format (Embroider compatibility), Dynamic Import not working with variable path. He suggested me to use the public folder as described in the create-react-app readme and to not import the SVGs via webpack: /* webpackChunkName: 'animal', webpackMode: 'eager' */, /* Can you write oxidation states with negative Roman numerals? You put it in like so: "syntax-dynamic-import". I needed 'babel-plugin-syntax-dynamic-import' in my .babelrc file. If youre using HTTPS is even worse! 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. My app is made to be accessible from a lot of specific platforms like mobile, desktop, tablet, VR and can be even more in the future!. All the modules which match the import's pattern will be part of the same main chunk. The compiler ensures that each dependency is available. Using it in an async function may not have the expected effect. Environments which do not have builtin support for Promise, like Internet Explorer, will require both the promise and iterator polyfills be added manually. It's subject to automatic issue closing if there is no activity in the next 15 days. Similar one works for me ( not exactly the same version of Webpack though ), Try to add one more comment to force code splitting. CommonJS or AMD modules cannot be consumed. However, there's likely a reasonable amount of optimization that can still be done. Hopefully, at this point, things make more sense when it comes to using import with dynamic arguments. You signed in with another tab or window. // In this example, the page shows an `input` tag and a button. In other words, it keeps track of modules' existence. 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. webpack.config.js. Do I need a thermal expansion tank if I already have a pressure tank? | by Geoff Miller | CloudBoost Write Sign up Sign In 500 Apologies, but something went wrong on our end. 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. just load them when used. Simple example: This can be verified in our example: after starting the server, try to require any of the modules present in the animals directory. Also I am using the svg-inline-loader. Adding asssets outside of the module system. Pablo Montenegro 38 Followers https://pablo.gg Follow More from Medium Gejiufelix in 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. 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. Is there a single-word adjective for "having exceptionally strong moral principles"? Is it possible to rotate a window 90 degrees if it has the same length and width? When the asset's content changes, [contenthash] will change as well. You signed in with another tab or window. Configuring webpack can be tricky when there are so many things going on. Would anyone have any ideas as to why webpack wouldn't create the chunk files? Using fetch I could load the images dynamically from the public folder and start webpack without getting ever again a memory issue. Entrypoint anytime = anytime.css anytime.bundle.js rev2023.3.3.43278. to your account, __webpack_require__ is called with result of promise external when it's is loaded as dynamic import, which results with error The keyword here is statically. This way, all the file paths will be promptly available when your app loads the parent bundle/chunk. If this function returns a value, this value is exported by the module. How to use Slater Type Orbitals as a basis functions in matrix method correctly? Already on GitHub? Thank you for looking at this maksim. Where does this (supposedly) Gibson quote come from? I'm creating react component libraries, which I'm then using to lazy load as routes, but while this works with a static import: const LazyComponent = lazy(() => import('my-package')), const packageOne = 'my-package' 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 . In old versions of Webpack (v1), we commonly used the AMD require or the specific Webpack require.ensure to dynamic load modules. 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. node --max_old_space_size=8000 scripts/start.js. Dynamic imports - this is my method of code splitting (page by page). Is it possible to make webpack search this file from node_modules? Now I have to do some refactoring in my app, but thats not a problem. It's totally understandable that webpack is a bundler and it should not take care of loading script from another domain. Find centralized, trusted content and collaborate around the technologies you use most. It's because I am using the presets in Babel; comments are on by default. rev2023.3.3.43278. How do I remove a property from a JavaScript object? If you want to check the how-to make a lazy-loaded single page application (SPA) using the discussed dynamic import, you can check out two of my previous articles on this subject. What sort of strategies would a medieval military use against a fantasy giant? Just an update for those going down this path: If you are using React, I would recommend react-loadable, makes it extremely easy to do dynamic imports on a per-component basis a lot of large companies use it. 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. 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. More specifically, considering the same file structure. So, your initial bundle size will be smaller. Let's take a deep dive into docker volume & its configuration options. The following is tested with Webpack 2, but should also work with v.1. // variable will be executed and retrieved. Geoff Miller 84 Followers Frontend Engineer @ Signifyd.com (we are hiring!) What is the !! Euler: A baby on his lap, a cat on his back thats how he wrote his immortal works (origin? require.ensure([], function(request) { request('someModule'); }) isn't handled by webpack's static parser. It is recommended to treat it as an opaque value which can only be used with require.cache[id] or __webpack_require__(id) (best to avoid such usage). 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). How to check whether a string contains a substring in JavaScript? [10] ./sources/views/admin/subscriptions.js 9.79 KiB {0} [built] (http-server is included for easy development) $ npm install --save-dev typescript ts-loader webpack http-server + webpack http-server + Based on the default configuration, our initial expression ./animals/${fileName}.js will result in ./animals/. NOTE: This plugin is included in @babel/preset-env, in ES2020. At the same time, webpack is preventing this by throwing the Module not found error. Sign up for a free GitHub account to open an issue and contact its maintainers and the community. to your account, What is the current behavior? But I'm not being able to dynamically load external libraries from variables. you are just linking to stuff outdated links. And this is what is causing all the trouble. In Webpack normally we load images as modules using the file loader. The provided argument will eventually result into a RegExp object which will be used to determine which files should be considered later. Flask api hosted as a docker container works with localhost:5000 but not with 172.17..2:5000; Python Flask heroku application error; Failed to compute cache key: "/films" not found: not found? To solve the problem of dynamic loading files, we can simply choose the loading strategy: This will force Webpack to include the file chunk inside the parent bundle/chunk, forcing it to not create a separated chunk for that. 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. If the current behavior is a bug, please provide the steps to reproduce. How Webpack Handles Dynamic Imports with Variable Paths | JavaScript in Plain English Write Sign up Sign In 500 Apologies, but something went wrong on our end. It's able to require modules without indicating they should be bundled into a chunk. If Magic Comments (or Any Comment) are not reaching the webpack, then they are lost in the transpiling process. webpackChunkName not effective and working with Babel? 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. When using CommonJS module syntax, this is the only way to dynamically load dependencies. Also, if this one doesnt work, try to move the loaded file outside of views folder. Already have an account? Sign in Subscribe to the blog to receive new posts right to your inbox. require.resolveWeak is the foundation of universal rendering (SSR + Code Splitting), as used in packages such as react-universal-component. Unfortunately I found it's more complex than I expected to fix it, I'm going to close my pull request so anyone interested in it can continue. You also need to know that fully dynamic statements such as import (pathToFile) will not work because webpack requires at least some file location information. It's used in conjunction with import() which takes over when user navigation triggers additional imports. As you are using [contenthash] in the output file names, only the changed modules will be cached again by service workers, not all the files. If you want the Chunks to be named properly; I would suggest going through the following checklist: Let me know through comments ? By clicking Sign up for GitHub, you agree to our terms of service and By default webpack import all files from views folder, which can conflict with code splitting. In this way, you only load the code that you need. 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. A big thanks to Dan Abramov (creator of Redux). Time: 2813ms From the import('./animals/cat.js') statement, we can tell that the module exists in the app, but in order for it to be available, the #load-cat button must be clicked first. Notice how the chunk depends on the animal name. Asynchronous Module Definition (AMD) is a JavaScript specification that defines an interface for writing and loading modules. | 18 modules As a smart developer, you dont want to load the entire code for desktop if the user is on mobile, and vice versa. I'm trying to migrate my app to webpack 4. In this article, we will dive deep into the concept of dynamic expressions when it comes to the import function and hopefully, at the end, you will be more acquainted with the range of possibilities that this webpack's feature provides. [38] ./sources/styles/anytime.css 39 bytes {0} [built] How do I include a JavaScript file in another JavaScript file? As the import is a function receiving a string, we can do powerful things like loading modules using expressions. [5] ./sources/views/admin/win_add_subsuser.js 3.19 KiB {0} [built] I can build the jet-demos project files and the bundle files are created in /codebase/. In this situation, the cat.js file is a CommonJS module and the rest are ES modules: The StackBlitz app for this new example can be found here. This issue had no activity for at least three months. Ok, I do this for a lot of images, this turned into a big problem and because of this extra requests, the images are slower to load. { type:"header", template:"Dynamically imported UI" }. This will not work because of CORS policy. If I want to use the cat module, after clicking on the button, I should see a new request for the chunk which contains the module in question: As probably noticed, the console tells us that the chunk has been loaded, as well as the module it contains, namely the cat module. The public folder is useful as a workaround for a number of less common cases: You have thousands of images and need to dynamically reference their paths. Ive read everything I can find in the webpack documentation and every relevant link Google produces for two days with no luck. The generated code should be __webpack_require__.t(m, 6) instead of 7, If someone wants to send a PR the problem is somewhere in RuntimeTemplate.js probably in namespacePromise. Webpack Dynamic Import babel-plugin-syntax-dynamic-import . const LazyComponent = lazy(() => import(packageOne)). to your account, I made a vue component package my-custom-comp, which contains dynamic import: