title: How to distinguish PSD layer types using psd.js
body: <p>I use psd.js to parse a PSD file on the server side. I only want plain pixel/shape layers and text layers. So I'd like to check if a Photoshop layer</p>
  
  <ol>
  <li>is an adjustment layer</li>
  <li>has layer mask applied</li>
  <li>has vector mask applied</li>
  <li>has layer styles applied</li>
  <li>is a clipping mask</li>
  </ol>
  
  <p>I've already figured out situations 4 and 5.</p>
  
  <ol start="4">
  <li><code>layer.get('objectEffects')</code> returns an object if a layer has layer styles.</li>
  <li><code>layer.clippingMask()</code> returns an object if a layer is a clipping mask.</li>
  </ol>
  
  <p>For situations 1-3, I have no idea how to check. Or is it possible to check using PSD.js?</p>
  
  <p>BTW, PSD.js does have a <code>psd.tree().childrenAtPath('a_layer_path')[0].get('vectorMask')</code> method on layer nodes. However, the vector mask it refers to is different from the vector mask in Photoshop.</p>