title: event handler that uses 'this' keyword not working as expected
body: <p>Title may not be correct but i didnt know how to ask my question !
  I have encountered a problem with <code>this</code> keyword . While using it as in this code <code>&lt;input type="text" onkeyup="this.value=this.value.toUpperCase();"&gt;&lt;/input&gt;</code>
  it works perfectly. But when i allot a function on input element that uses <code>this</code> keyword , it dont work as in<br>
  HTML </p>
  
  <pre><code>&lt;input type="text" onkeyup="up();"&gt;&lt;/input&gt;
  </code></pre>
  
  <p>Javascript</p>
  
  <pre><code>function up()
  {   
      this.value=this.value.toUpperCase();
  }
  </code></pre>