title: Javascript: Check if something can have properties _added_ to it
body: <p>EDIT: Made clearer that the need is to determine if I can <em>add</em> properties to a value, not if a value can <em>have</em> its own properties.</p>
  
  <p>Is there a way to check if is possible to <em>add properties</em> to a <code>value</code>?</p>
  
  <p>For example, if I have this code:</p>
  
  <pre><code>function test( value ) {
      // return true if it is possible to add properties to value
  }
  </code></pre>
  
  <p>Other than actually adding a property <code>value</code> to test, is there a reliable way to deduce if <code>value</code> is something that properties can be added to?</p>
  
  <p>For example, I know an <code>object</code> can have properties and <code>undefined</code> can't, but I'm not keen on creating a list of known things that might not suffice in the future. Is something like <code>instanceof object</code> sufficient?</p>