A Bower Primer

Recently, I've been doing a fair bit of frontend development with my team as we've worked on the Apigility admin. This has meant working with a variety of both JavaScript and CSS libraries, often trying something out only to toss it out again later. Working with frontend libraries has been quite a hassle, due to a combination of discovery, installation issues, and build issues (minimization, primarily). I figured there must a better way.

Background

Until recently, discovery of JS and CSS libraries has gone something like this:

  1. Search for functionality via Google
  2. Generally find a solution on StackOverflow
  3. Discover said solution relies on a third-party library
  4. Google for said library
  5. Generally find said library on GitHub
  6. Clone the library locally
  7. Either build the final assets, or try and locate them in the repo
  8. Minimize the assets
  9. Copy the assets into the project

Frontend development sucks.

Then I started noticing these files called .bowerrc and bower.json in many of the aforementioned libraries, and also that Ralph had put some inside our Apigility skeleton. I got curious as to what this "bower" might be.

Bower: Package management for the web

Essentially, Bower is, to use the project's words, "a package manager for the web." Written in JavaScript, and running on node.js, it is to frontend assets what npm is to node, or Composer is to PHP. It allows you to define what assets you need in your application, including the versions, and then install them. If any of those assets have other dependencies, those, too, will be installed.

Later, you can update the dependencies, add or remove dependencies, and more.

On top of that, bower allows you to search for packages, which essentially allows you to eliminate most of the steps 4 and on in my list above.

A Bower Primer

So, how do you use bower?

In my experience, which is not extensive by any stretch, the usage is like this:

  1. Search for functionality via Google
  2. Generally find a solution on StackOverflow
  3. Discover said solution relies on a third-party library
  4. Use bower to search for said library
  5. Add the discovered library to your bower.json file
  6. Run bower install or bower update

I've found that most projects registered with bower have minimized builds available (as well as the full source build), which is a huge boon in terms of performance. It also eliminates the "minimize the assets" step from my original list.

To use bower, you'll need two files. The first is .bowerrc which goes in your project root; you'll run bower from this same directory. This file tells bower how to run, and where to install things, and, despite being an RC file, is written in JSON. Mine usually looks like this:


{
    "directory": "public/assets/vendor"
}

The above tells bower to install dependencies in the public/assets/vendor subdirectory.

The second file you need is bower.json. This file tells bower what asset packages you want to install, and the preferred version. (The file can also be used to define a package, just like with Composer or npm.) As an example, the following is a definition I used for an Apigility example:


{
    "name": "ag-contacts-demo",
    "version": "0.0.1",
    "ignore": [
        "**/.*"
    ],
    "dependencies": {
        "angular": "~1.2",
        "angular-resource": "~1.2",
        "angular-route": "~1.2",
        "bootstrap": ">=3.0.0",
        "font-awesome": "~3.2.1"
    }
}

Bower requires that packages use Semantic Versioning. You can specify exact versions, minor versions, or major versions, combine them with comparison operators (<, >, =, etc.), or use the "next significant release" operator ("~") to indicate a given version up to the next more general release (e.g., "~1.2" is equivalent to ">=1.2,<2.0").

Once you have these defined, you should also add an entry to your .gitignore file to exclude the directory you list in your .bowerrc; these files can be installed at build time, and thus help you keep your project repository lean. Per the above example:


public/assets/vendor/

At this point, run bower install, and bower will resolve all dependencies and install them where you want.

At any point, you can list what packages bower has installed, as well as the versions it has installed. The bower help command is your friend should those needs arise.

Closing Thoughts

I'm quite happy with the various tools emerging to make modern web development easier by allowing developers to more easily share their work, as well as ensure that all dependencies are easily installable. Bower is another tool in my arsenal as a web developer, giving me a consistent set of dependency management tools from my server-side development all the way to my client-side application.

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