title: What is "undefined x 1" in JavaScript?
body: <p>I'm doing some small experiments based on <a href="http://perfectionkills.com/understanding-delete/" rel="noreferrer"><strong><em>this blog entry</em></strong></a>.</p>
  
  <p>I am doing this research in Google Chrome's debugger and here comes the hard part.</p>
  
  <p><img src="https://i.stack.imgur.com/asltc.jpg" alt="What the heck is this?!"></p>
  
  <p>I get the fact that I can't delete local variables (since they are not object attributes). I get that I can 'read out' all of the parameters passed to a function from the array called 'arguments'. I even get it that I can't delete and array's element, only achieve to have <strong><code>array[0]</code></strong> have a value of undefined.</p>
  
  <p>Can somebody explain to me what <strong><code>undefined x 1</code></strong> means on the embedded image?</p>
  
  <p>And when I overwrite the function <strong><code>foo</code></strong> to return the <strong><code>arguments[0]</code></strong>, then I get the usual and 'normal' undefined.</p>
  
  <p>This is only an experiment, but seems interresting, does anybody know what <strong><code>undefined x 1</code></strong> refers to?</p>