title: Why do JavaScript converts some number values automatically
body: <p>I have worked the same process in JavaScript with number datatype</p>
  
  <pre><code>var num = 9223372036854775807;
  </code></pre>
  
  <p>But when I try print this variable in browser</p>
  
  <pre><code>alert(num)
  </code></pre>
  
  <p>the value changed to 9223372036854776000</p>
  
  <p>Any ideas?</p>