title: Javascript difference between {} and []
body: <p>I am working on javascript and I run into this:</p>
  
  <p>if i do </p>
  
  <pre><code>let object = {};
  object.length
  </code></pre>
  
  <p>It will complain that object.length is undefined 
  But </p>
  
  <pre><code>let object = [];
  object.length 
  </code></pre>
  
  <p>works</p>
  
  <p>Any know why?</p>
  
  <p>Thanks</p>