title: What kinds of changes do ViewChildren and ContentChildren QueryLists listen for?
body: <p>Let's say you had the following code:</p>
  
  <p><a href="https://i.stack.imgur.com/7IFx1.png" rel="noreferrer"><img src="https://i.stack.imgur.com/7IFx1.png" alt="&lt;code&gt;@ViewChildren(&#39;item&#39;) items: QueryList&lt;any&gt;;&lt;/code&gt;"></a></p>
  
  <p>And somewhere else the code:</p>
  
  <p><a href="https://i.stack.imgur.com/qac0F.png" rel="noreferrer"><img src="https://i.stack.imgur.com/qac0F.png" alt="&lt;code&gt;this.items.changes.subscribe(() =&gt; {})&lt;/code&gt;"></a></p>
  
  <p>What are the changes that would cause <code>() =&gt; {}</code> to be called? What about <code>@ContentChildren()</code>? I couldn't find any documentation on this.</p>
  
  <p>Additionally, is there a way to get more information about the change that happened? (e.g. the type of change, the element with which the change occurred, etc.)</p>
  
  <p>EDIT: The answer to the "Additionally" portion above can be found in the comments section of the answer that is marked correct.</p>