<p dir="auto">I tried several combinations. Nothing works:</p>
<div class="highlight highlight-source-js notranslate position-relative overflow-auto" dir="auto" data-snippet-clipboard-copy-content="function decorator(Class) { return Class; }

@decorator
class B { }"><pre class="notranslate"><span class="pl-k">function</span> <span class="pl-en">decorator</span><span class="pl-kos">(</span><span class="pl-v">Class</span><span class="pl-kos">)</span> <span class="pl-kos">{</span> <span class="pl-k">return</span> <span class="pl-v">Class</span><span class="pl-kos">;</span> <span class="pl-kos">}</span>

@<span class="pl-s1">decorator</span>
<span class="pl-k">class</span> <span class="pl-v">B</span> <span class="pl-kos">{</span> <span class="pl-kos">}</span></pre></div>
<div class="highlight highlight-source-json notranslate position-relative overflow-auto" dir="auto" data-snippet-clipboard-copy-content="{
  &quot;presets&quot;: [&quot;es2015&quot;, &quot;stage-0&quot;],
  &quot;plugins&quot;: [ &quot;transform-decorators&quot;, &quot;syntax-decorators&quot;]
}"><pre class="notranslate">{
  <span class="pl-ent">"presets"</span>: [<span class="pl-s"><span class="pl-pds">"</span>es2015<span class="pl-pds">"</span></span>, <span class="pl-s"><span class="pl-pds">"</span>stage-0<span class="pl-pds">"</span></span>],
  <span class="pl-ent">"plugins"</span>: [ <span class="pl-s"><span class="pl-pds">"</span>transform-decorators<span class="pl-pds">"</span></span>, <span class="pl-s"><span class="pl-pds">"</span>syntax-decorators<span class="pl-pds">"</span></span>]
}</pre></div>
<p dir="auto">result (decorator just silently ignored):</p>
<div class="highlight highlight-source-js notranslate position-relative overflow-auto" dir="auto" data-snippet-clipboard-copy-content="...
var B = function B() {
  _classCallCheck(this, B);
};"><pre class="notranslate">...
<span class="pl-k">var</span> <span class="pl-v">B</span> <span class="pl-c1">=</span> <span class="pl-k">function</span> <span class="pl-v">B</span><span class="pl-kos">(</span><span class="pl-kos">)</span> <span class="pl-kos">{</span>
  <span class="pl-en">_classCallCheck</span><span class="pl-kos">(</span><span class="pl-smi">this</span><span class="pl-kos">,</span> <span class="pl-v">B</span><span class="pl-kos">)</span><span class="pl-kos">;</span>
<span class="pl-kos">}</span><span class="pl-kos">;</span></pre></div>
<p dir="auto">with this order: <code class="notranslate">["stage-0", "es2015"]</code><br>
it throws an error <code class="notranslate">TypeError: src/mxn/decorators.func.test.js: Property right of AssignmentExpression expected node to be of a type ["Expression"] but instead got "Decorator"</code></p>