What does += %w mean in the line used to precompile assets in assets.rb? : <p>I'm looking at the default file placed in <code>/config/initializers/assets.rb</code> in a Rails 5 app.</p>

<p>To precompile code, Rails inside the comments, gives a pre-existing code to precompile assets together.</p>

<pre><code>Rails.application.config.assets.precompile += %w( search.js )
</code></pre>

<p>I am curious what the last part means: <code>+= %w( search.js )</code>, as I have never seen the expression (<code>+= %w</code>) used in Ruby or Rails. I know that the entire line is calling the Rails class, chaining some methods together to create the end output. But I am curious, what does the += %w do, and how is it affecting what I presume to be the argument (<code>search.js</code>)?</p>
