title: Are nodejs data-structures thread-safe by design?
body: <p>Read in a node.js related web document that it is a single threaded server. So it confuses me whether all data structures by default be thread-safe in a node server!</p>
  
  <p>I have multiple call-backs accessing a global object like this : </p>
  
  <pre><code>callback1{
  global_var['key'] = val;
  }
  
  callback2{
  globalv_var['key'] = val;
  }
  </code></pre>
  
  <p>'key' may be same at times and may be different as well. Will the global_var be thread-safe ?
  callbacks, as intended gets called back as and when something is done, in no particular order.</p>