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ToggleIntroduction To WebPack Interview Questions & Answers
WebPack is a tool that has gotten a lot of attention in the last few years, and it is now seen used in almost every project. Interviewers often ask numerous WebPack Questions to people that are seeking jobs in the tech world. WebPack is a tool that lets you compile JavaScript modules, also known as a module bundler. Given a large number of files, Webpack helps to generate a single file or a few files that run user applications.
Webpack can perform many operations like it helps the users bundle their resources. It also watches for changes and re-runs the tasks. Webpack can run Babel transpiler to ES5, allowing the user to use the latest javascript features without worrying about browser support. It can transpile CoffeeScript to JavaScript without much hassle. And it can also convert online images to data URIs.
Webpack allows its users to use require() for CSS files. It can run a development web server and can handle hot module replacement. It can split the output files into multiple files, to avoid having a huge js file to load in the first page hit. Webpack can also perform tree shaking. Webpack is not limited to being used on the frontend, it’s also useful in backend Node.js development.
All these usages of Webpack make it highly popular among organizations. If you too want to get the dream job at your organization having detailed knowledge in Webpack will make you a sure shot and every interviewer’s favorite. This article will surely help you delve deep into the basics, intermediate, and advanced question levels of Webpack and make you an ace at your next interview.
Webpack Interview Questions For Freshers
What is Webpack?
Webpack is a module bundler for JavaScript applications. Webpack recursively builds every module in the user application, then packs all those modules into a small number of bundles. It is a free and open-source module bundler for JavaScript. It is made primarily for JavaScript, but it can transform front-end assets such as HTML, CSS, and images if the corresponding loaders are included.
Webpack takes modules with dependencies and generates static assets representing those modules. The interviewer can ask you these Webpack interview questions to test your knowledge of WebPack basics.
How can webpack construction speed be increased?
A user can increase the speed of webpack construction by the following methods:
- Method 1: A common chunk plugin is used in the case of multiple entries to extract public code. Externals configuration allows you to extract common libraries. To precompile NPM packages that we will reference but never modify, use dllplugin and dllreferenceplugin. Multi-threaded compilation with the happy pack.
- Method 2: Improve the compression speed of uglify plugin by using webpack – uglify – parallel. A multi-core parallel compression algorithm is used by webpack uglify parallel in order to improve compression speed. Reduce redundant code by using tree shaping and scope hosting.
The interviewer can ask you these Webpack interview questions to test your knowledge of Webpack basics.
What is the use of loaders in webpack?
Loaders are used in webpack for the following purposes:
PURPOSE1: In a loader, the source code of a module is transformed. Modules written in a variety of languages and preprocessors can be loaded by webpack using loaders. |
PURPOSE2: When loading non-javaScript modules, loaders tell webpack how to include these dependencies in bundles. |
The interviewer can ask you these Webpack interview questions to test your knowledge of Webpack basics.
What are the advantages of using Webpack?
The advantages of using Webpack are as follows:
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The interviewer can ask you these Webpack interview questions to test your knowledge of Webpack basics.
What is a plugin in Webpack?
A webpack plugin is a JavaScript object that has an application method. This application method is called by the webpack compiler, giving access to the entire compilation lifecycle. Plugins are the backbone of webpack. Webpack itself is built on the same plugin system that you use in your webpack configuration. They also serve the purpose of doing anything else that a loader cannot do. Webpack provides many plugins out of the box. Since plugins can take arguments/options, a user must pass a new instance to the plugins property in your webpack configuration. Depending on how users are using webpack, there are multiple ways to use plugins.
The interviewer can ask you these Webpack interview questions to test your knowledge of the key characteristics of Webpack. It is also among the frequently asked Webpack interview questions.
What are loaders in Webpack?
Loaders are transformations that are applied to the source code of a module. They allow you to pre-process files as you import or “load” them. Thus, loaders are kind of like “tasks” in other build tools and provide a powerful way to handle front-end build steps. Loaders can transform files from a different language like TypeScript to JavaScript or load inline images as data URLs. Loaders even allow you to do things like import CSS files directly from the user JavaScript modules. The interviewer can ask you these Webpack interview questions to test your knowledge of Webpack basics.
How can a user install Webpack?
There are two ways to install Webpack:
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- LOCAL INSTALL- Webpack can be installed locally as well. It’s the recommended setup because webpack can be updated per project, and you have less resistance to using the latest features just for a small project rather than updating all the projects you have that use webpack. There are two ways to locally install Webpack:
- With Yarn: yarn add webpack webpack-cli -D
- With npm: npm I webpack webpack-cli –save-dev, Once this is done, add this to your package.json file, once this is done, you can run webpack by typing, in the project root.
- GLOBAL INSTALL- Here’s how to install Webpack globally with Yarn:
On yarn, globally add webpack, Click Webpack with npm. Now on npm i -g webpack click on it, once this is done, you should be able to run webpack-cli.
The interviewer can ask you these Webpack interview questions to test your knowledge of the key characteristics of Webpack. It is also among the frequently asked Webpack interview questions.
How is Webpack Configuration done?
By default, webpack starting from version 4 does not require any sort of configuration if the user takes care of the following conventions:
- the entry point of your app is ./src/index.js
- the output is put in ./dist/main.js.
- Webpack works in production mode
The user can customize every little bit of webpack of course according to their need. The webpack configuration is stored in the webpack.config.js file, in the project root folder. The interviewer can ask you these Maven interview questions to test your basic understanding.
What is the Webpack Mode?
The Webpack Mode was introduced in webpack 4. The mode sets the environment in which the webpack works. It can be set to development or production even though by default it is set to production, so the user has to only set it when moving to development. The following code defines the development mode in Webpack:
The interviewer can ask you these Maven interview questions to test your basic understanding.
What is the difference between development and production mode in Webpack?
The difference between development and production mode in Webpack is defined in the table below:
DEVELOPMENT MODE | PRODUCTION MODE |
Development Mode builds very fast. | Production mode is slower to build. |
Development Mode generates a less optimized bundle than production mode. | Production mode generates a more optimized bundle. |
Development Mode does not remove comments and provides more detailed error messages and suggestions. | The resulting JavaScript file is smaller in size, as it removes many things that are not needed in production. |
The interviewer can ask you these Webpack interview questions to test your knowledge of the key characteristics of Webpack. It is also among the frequently asked Webpack interview questions.
Webpack Interview Questions For Intermediate Level
What are the important plugins in Webpack?
Some of the important plugins in Webpack are given in the table below:
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The interviewer can ask you these Webpack interview questions to evaluate your understanding of plugins. It is also among the frequently asked Webpack interview questions.
Why does Webpack give the users a dependency graph?
The webpack gives the users a dependency graph any time one file depends on another, webpack treats this as a dependency. This allows webpack to take non-code assets, such as images or web fonts, and also provide them as dependencies for the user application.
When webpack processes the application, it starts from a list of modules defined on the command line or in its configuration file. Starting from these entry points, webpack recursively builds a dependency graph that includes every module that the user application needs, then packages all of those modules into a small number of bundles.
The interviewer can ask you these Maven interview questions to evaluate your understanding of the dependency graph. It is also among the frequently asked Webpack interview questions.
How does Webpack transform the JavaScript files?
Webpack is a module bundler. Its main purpose is to bundle JavaScript files for usage in a browser, yet it is also capable of transforming. If the user chooses to write code in JavaScript ES6 which is not understood by all browsers, Webpack will transform that file into a version of JavaScript that can be ready by all browsers.
The interviewer can ask you these Maven interview questions to evaluate your understanding of Webpack. It is also among the frequently asked Webpack interview questions.
How to generate Source Maps in Webpack?
Since webpack bundles the code, Source Maps are mandatory to get a reference to the original file that raised an error, for example, The user tells webpack to generate source maps using the devtool property of the configuration. Devtool has many possible values, the most used probably are
- None: It adds no source maps.
- Source Map: It is ideal for production, provides a separate source map that can be minimized, and adds a reference into the bundle, so development tools know that the source map is available. Of course, the user should configure the server to avoid shipping this, and just use it for debugging purposes.
- Inline Source Map: It is ideal for development, inlines the source map as a Data URL.
The interviewer can ask you these Webpack interview questions to evaluate your understanding of source maps. It is also among the frequently asked Webpack interview questions.
What is React Code in Webpack?
React is a declarative, efficient, and flexible JavaScript library for building user interfaces. It lets you compose complex UIs from small and isolated pieces of code called components. The following react code can be added to the file by the user while using webpack:
The interviewer can ask you these Webpack interview questions to evaluate your understanding of react codes. It is also among the frequently asked Webpack interview questions.
What are bundles in Webpack?
When Webpack processes the user application, it builds a dependency graph that maps out the modules that the user project needs and generates one or more bundles. A bundle is a distinct grouping of connected code that has been compiled and transformed for the browser. If one file depends on another then it uses the code from a separate file, Webpack treats this as a dependency. Webpack also takes the user’s non-code assets like images, fonts, styles, etc., and converts them to dependencies for the user application.
Bundles are produced from a number of distinct modules, bundles contain the final versions of source files that have already undergone the loading and compilation process. The interviewer can ask you these Webpack interview questions to evaluate your understanding of bundles. It is also among the frequently asked Webpack interview questions.
What is bundle splitting in Webpack?
Bundles are Produced from a number of distinct modules, bundles contain the final versions of source files that have already undergone the loading and compilation process. Bundle Splitting in Webpack is the process that offers one way of optimizing a build, allowing webpack to generate multiple bundles for a single application. Bundling Javascript code into several files is known as bundle splitting.
It enables only a tiny amount of code to be downloaded with the initial page load, while other sections of the web app are loaded as required later. The interviewer can ask you these Webpack interview questions to evaluate your understanding of bundle splitting in Webpack. It is also among the frequently asked Webpack interview questions.
How can a user watch changes in Webpack?
The user can watch changes in the Webpack by adding a few scripts to the code. Webpack can automatically rebuild the bundle when a change in user application happens, and it keeps listening for the next change. One nice feature of the watch mode is that the bundle is only changed if the build has no errors. If there are errors, the watch will keep listening for changes, and try to rebuild the bundle, but the current, working bundle is not affected by those problematic builds. The following steps will make it clearer:
STEP 1: First add the following script,
STEP 2: And the run from the following three options:
- Nmp run watch
- Yarn run watch
- Yarn watch
The interviewer can ask you these Webpack interview questions to evaluate your understanding of Webpack. It is also among the frequently asked Webpack interview questions.
How to handle images in Webpack?
Webpack allows its users to use images in a very convenient way, using the file-loader loader. The steps to handle images in Webpack are as follows:
STEP 1: First use the configuration given below,
STEP 2: The configuration allows the user to import images in JavaScript
STEP 3: The user can also handle images with the help of the URL-Loader loader in Webpack.
The interviewer can ask you these Webpack interview questions to evaluate your understanding of handling images Webpack. It is also among the frequently asked Webpack interview questions.
What are the benefits of Webpack?
Webpack goes through your package and creates what it calls a dependency graph which consists of various modules which the user web application would require to function as expected. Then, depending on this graph, it creates a new package that consists of the very bare minimum number of files required, often just a single bundle.js file that can be plugged into the HTML file easily and used for the application. The interviewer can ask you these Webpack interview questions to evaluate your understanding of Webpack. It is also among the frequently asked Webpack interview questions.
Webpack Interview Questions For Advance Level
What is the main difference between webpack and other build tools like gulp or grunt?
WEBPACK | GULP/ GRUNT |
Webpack is a highly popular module bundler. | Gulp or Grunt is a less used task runners. |
It offers more flexibility and advanced functionality for modern front-end projects. | Gulp or Grunt is less flexible compared to Webpack. |
Webpack analyzes the whole project. It looks through all the dependencies, processes them with loaders, and produces a bundled JS file. | Gulp or Grunt looks into a defined path for files that match the user configuration. |
It comes with a functional core and can be extended using particular loaders and plugins. | Gulp or grunt can not be extended. |
The interviewer can ask you these Webpack interview questions to examine your knowledge of its benefits over other tools like Gulp or Grunt.
What is the environment in which Webpack works?
Webpack works in the Node JS environment. Node JS is an extremely powerful framework developed on Chrome’s V8 JavaScript engine that compiles the JavaScript directly into the native machine code. It is a lightweight framework used for creating server-side web applications and extends JavaScript API to offer usual server-side functionalities. It is generally used for large-scale application development, especially for video streaming sites, single-page applications, and other web applications. The interviewer can ask you these Webpack interview questions to examine your knowledge of on Webpack Environment.
Which modules design patterns does webpack support out of the box?
Since Webpack 2 the following modules’ design patterns are supported in Webpack:
COMMON JS- CommonJS module is a reusable piece of JavaScript that exports specific objects made available to any dependent code. Unlike AMD, there are typically no function wrappers around such modules. |
AMD MODULE- Asynchronous module definition (AMD) is a specification for the programming language JavaScript. It defines an application programming interface (API) that defines code modules and their dependencies and loads them asynchronously if desired. |
ES6 MODULE – Modules in ES6 are an essential concept. Although it is not available everywhere, today we can use it and can transpile it into ES5 code. Transpilation is the process of converting the code from one language into its equivalent language. The ES6 module transpiler tool is responsible for taking the ES6 module and converting it into a compatible code of ES5 in the AMD. |
The interviewer can ask you these Webpack interview questions to examine your knowledge of Webpack Modules.
What is the way of working of Loaders in Webpack?
The loaders work in an Asynchronous as well as Synchronous way in Webpack as loaders can be synchronous or asynchronous. It is defined in the table below:
SYNCHRONOUS | ASYNCHRONOUS |
Synchronous loaders can return a single value representing the transformed module. In more complex cases, the loader can return any number of values by using this. callback(err, values…) function. Errors are either passed to this. callback function or thrown in a synchronous loader. | Loaders were originally designed to work in synchronous loader pipelines, like Node. js using enhanced-require, and asynchronous pipelines, like in webpack. |
The interviewer can ask you these Webpack interview questions to examine your knowledge of Webpack Loaders.
What are module dependencies in Webpack?
Depending on the type of module, there may be a different schema used to specify dependencies. In CSS for example, the import and URL statements are used. These dependencies should be resolved by the module system. This can be done in one of two ways:
- By transforming them to require statements- The CSS-loader is a good example of the first approach. It transforms dependencies to requires, by replacing the import statements with a require to the other stylesheet and URL with a require to the referenced file.
- Using the “this. resolve” function to resolve the path- In the case of the less-loader, it cannot transform each import statement to a require because all .less files must be compiled in one pass for variables and mixin tracking. Therefore, the less loader extends the less compiler with custom path resolving logic. It then takes advantage of the second approach, this. resolve, to resolve the dependency through webpack.
What is the difference between Simple and Complex Usage of Loaders in Webpack?
The difference between Simple and Complex usage of loaders in Webpack is given in the table below:
SIMPLE USAGE OF LOADERS IN WEBPACK | COMPLEX USAGE OF LOADERS IN WEBPACK |
When a single loader is applied to the resource, the loader is called with only one parameter that is a string containing the content of the resource file. The loader is expected to give back one or two values. The first value is a resulting JavaScript code as a string or buffer. The second optional value is a SourceMap as a JavaScript object. | When multiple loaders are chained, it is important to remember that they are executed in reverse order which is either right to left or bottom to top depending on the array format. The last loader, called first, will be passed the contents of the raw resource. The first loader, called last, is expected to return JavaScript and an optional source map. The loaders in between will be executed with the results of the previous loader in the chain. |
The interviewer can ask you these Webpack interview questions to examine your knowledge of on usage methodology of Webpack Loaders.
What is the advantage of the Compression plugins in Webpack?
The advantages of Compression Plugin Webpack are given below:
- Compression Plugin builds a zipped version of bundles. It’s possible to simply add server-side compression e.g using Nginx or an express compression plugin. Server-side compression is not recommended because it adds load on the CPU and increases response time.
- Compressing static files during the build steps is still a moot topic. Some people argue that it is up to the webserver to compress the files. In fact, today web servers do not really optimize the compression of static files. When the user compresses during the build then they easily see the complete size of their web application which is great for tracking web application performances.
- With the help of the compression plugin in Webpack, the user application is much more portable the user can easily change their deployment or their web server with pre-compressed assets.
The interviewer can ask you these Webpack interview questions to examine your knowledge of Webpack plugins.
Also Read: Maven Interview Questions , Angular Interview Questions , Amazon Data Scientist Interview Questions
Conclusion
Webpack is a great tool that lets its users compile JavaScript modules, also known as a module bundler. Given a large number of files, it generates a single file or a few files that run the user application. It can perform many operations and helps its users bundle their resources. Webpack is a tool that has gotten a lot of attention in the last few years, and it is now seen used in almost every project.
Interviewers often ask numerous Webpack Questions to people that are seeking jobs in the tech world. A solid understanding of the Webpack can make your interviews exciting. We are certain that most of your concerns about Webpack Interview Questions have been addressed through this insightful blog. We have gathered a wide range of Webpack Interview Questions that are frequently asked in the interviews.
Frequently Asked Questions
Webpack is a module bundler for javascript applications. Webpack recursively builds every module in the user application, then packs all those modules into a small number of bundles. It is a free and open-source module bundler for Javascript.
It is made primarily for JavaScript, but it can transform front-end assets such as HTML, CSS, and images if the corresponding loaders are included. Webpack takes modules with dependencies and generates static assets representing those modules. Let’s move on to the next faq for the Webpack Interview Questions blog.
Webpack goes through your package and creates what it calls a dependency graph which consists of various modules which the user web application would require to function as expected.
Then, depending on this graph, it creates a new package that consists of the very bare minimum number of files required, often just a single bundle.js file that can be plugged into the HTML file easily and used for the application. The interviewer can ask you these Webpack interview questions to evaluate your understanding of Webpack. Let’s move on to the next faq for the Webpack Interview Questions blog.
Webpack is a tool that lets you compile JavaScript modules, also known as a module bundler. Given a large number of files, Webpack helps to generate a single file or a few files that run user applications.
It is made primarily for JavaScript, but it can transform front-end assets such as HTML, CSS, and images if the corresponding loaders are included. Webpack takes modules with dependencies and generates static assets representing those modules. Let’s move on to the next faq for the Webpack Interview Questions blog.
Webpack is a module bundler for javascript applications. Webpack recursively builds every module in the user application, then packs all those modules into a small number of bundles.
It takes disparate dependencies, creates modules for them, and bundles the entire network up into manageable output files. Let’s move on to the next faq for the Webpack Interview Questions blog.
Loaders are transformations that are applied to the source code of a module. They allow the users to pre-process files to either import or load them. Thus, loaders are kind of like tasks in other build tools and provide a powerful way to handle front-end build steps.
In a loader, the source code of a module is transformed. Modules written in a variety of languages and preprocessors can be loaded by webpack using loaders. Let’s move on to the next faq for the Webpack Interview Questions blog.
A webpack plugin is a JavaScript object that has an application method. This application method is called by the webpack compiler, giving access to the entire compilation lifecycle.
Plugins work at the bundle or chunk level and usually work at the end of the bundle generation process. Let’s move on to the next faq for the Webpack Interview Questions blog.
The difference between loaders and plugins in Webpack is:
LOADERS | PLUGINS |
Loaders work at the individual file level during or before the bundle is generated. | Plugins work at the bundle or chunk level and usually work at the end of the bundle generation process. |
Let’s move on to the next faq for the Webpack Interview Questions blog.
The entry object is where webpack looks to start building the bundle. The context is an absolute string to the directory that contains the entry files. The point or points where to start the application bundling process.
If an array is passed then all items will be processed. A dynamically loaded module is not an entry point. Let’s move on to the next faq for the Webpack Interview Questions blog.
BABEL | WEBPACK |
Babel is a toolchain that is mainly used to convert ECMAScript 2015+ code into a backward-compatible version of JavaScript in current and older browsers or environments. It transforms syntax. | Webpack is a module bundler for javascript applications. Webpack recursively builds every module in the user application, then packs all those modules into a small number of bundles. It is a free and open-source module bundler for Javascript. It is made primarily for JavaScript, but it can transform front-end assets such as HTML, CSS, and images if the corresponding loaders are included. Webpack takes modules with dependencies and generates static assets representing those modules. |
Let’s move on to the next faq for the Webpack Interview Questions blog.
WEBPACK | npm |
Webpack is a module bundler for javascript applications. Webpack recursively builds every module in the user application, then packs all those modules into a small number of bundles. It is a free and open-source module bundler for Javascript. | npm is the package manager for the Node JavaScript platform. It puts modules in place so that nodes can find them, and manages dependency conflicts intelligently. It is extremely configurable to support a wide variety of use cases. |