When comparing Duo vs Bower, the Slant community recommends Bower for most people. In the question“What are the best open source front-end package managers?” Bower is ranked 5th while Duo is ranked 6th. The most important reason people chose Bower is:
Bower is flexible enough that you can manage pretty much any package you would need on the front-end, so you can manage all your dependencies with one tool, including CSS, boilerplate, fonts and more.
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Pros
Pro Handles the entire build and packaging process for you
Because Duo allows you to require dependencies directly in your html, css, and javascript, you don't need to manage annoying build processes. Duo automatically supports preprocessed languages like Coffeescript and Sass, and automatically bundles them into a single file, making it an easy-to-use, all-in-one tool. All you have to do is run duo in > out
and you're done!
Pro Allows you to directly require dependencies from Javascript, HTML, and CSS
With Duo you don't need to manage a separate dependency file, you just require projects from your files where you need them. It works with all front-end languages, giving you powerful inline Javascript, HTML, CSS, and even JSON management in a way that no other package manager supports.
Pro Require directly from github
Duo allows you to use require
to import packages directly from github using the username/package_name@version
syntax. The version is optional, in case you want to test out a new package quickly.
Pro Built on top of Component
Duo can be seen as an easier to use, more feature complete wrapper around component.
Pro Supports both Bower and Component packages
Duo is primarily designed to support Component packages, but Bower package support is available with npm support planned, so you can use Duo with libraries as well as components.
Pro Manages non-JavaScript components
Bower is flexible enough that you can manage pretty much any package you would need on the front-end, so you can manage all your dependencies with one tool, including CSS, boilerplate, fonts and more.
Pro Simplicity provides more flexibility
Bower doesn't try to handle too much of the workflow process, which means it's more flexible, and can be incorporated into more workflows. It tries to just do package management well and nothing else, which is why so many workflow wrappers support it. Because it doesn't try to do too much vertical integration, it also means that the list of supported components that it manages is huge.
Pro Largest front-end specific package registry
Although npm is the largest javascript package manager, Bower is the most popular one built specifically for the front-end. With over 16000 components in its registry, pretty much every component you can think of is supported.
Pro Easily integrates with other tools
Because of Bower's focus on simplicity, it makes it much easier to integrate with other tools, so it has a wide range of support with workflow wrappers and task managers such as yeoman and grunt.
Pro Requires a flat dependency tree
While nested dependencies are better for backend modules that need lots of inter-dependency, they lead to bloated file sizes. Flat dependencies are better for frontend optimization, where file size needs to be more closely managed.
Pro Does not store components in a registry
You always get package directly from owner's repository, i.e. you will always get latest version as soon as its version tag is committed without need of waiting until owner publishes updated package.
Pro Simpler to manage varied code
Because Bower makes few assumptions about the source and format of packages, it's easier to apply it to more of your packages
Pro AMD & CJS compatible
Bower strives to be as simple of a package manager as possible and puts as few restrictions on the packages in the registry as possible, making it the most flexible package manager with the most potential packages.
Cons
Con Harder to manage versions between files
Because versions and dependencies can be specified inline, it might be harder to update your packages when you want to upgrade. (However, it is possible to specify dependencies in a JSON file.)
Con Cannot extract modules from a bundle and put into another one
As for common modules shared by multiple pages, duo.js cannot extract and put them into another bundle which is loaded commonly. On the other hand, modules modified rarely should put into another bundle so they can be still cached when other modules change.
Con Seems like a redundant package manger
NPM with Webpack/Browserify can handle all the dependencies for both back-end and front-end. The only place where Bower may be useful is for projects which use libraries not supported by NPM, such as Polymer.
Con Deprecated
As of May 2017 Bower has been deprecated and will not receive any updates with new features. Bugs will still be fixed though for existing projects that use Bower.
Con Does not store components in a registry
Bower installs components directly from urls and repositories, which makes it more susceptible to components being taken down, with fewer guarantees about their availability.
Con Difficult to create bundles
To create a minified bundle of all the required JS dependencies other tools need to be used.
For example a JavaScript task runner which will automatically concatenate JavaScript files and minify them will be needed. Although it's done automatically, it's still extra work because the task runner needs to be configured.
Con Lack of signing of packages on the repository
Anyone can register their package on Bower's GIT registry - on one side, this brings a lot of ease to developers, but on the other hand, this can lead to security issues because the packages are not signed.
Con Less packages than npm due to a smaller ecosystem
- Bower: 36,000 packages
- Npm: 161,876 total packages (of course, many work only on the server)