title: Debugging a simple Javascript error
body: <p>I am trying to move down a div container with Id( topleft) using java script, but my java script code has a problem. Logically, it should work, can someone check? </p>
  
  <p>HTML code</p>
  
  <pre><code>&lt;html&gt;
      &lt;title&gt;Test&lt;/title&gt;
      &lt;head&gt;
          &lt;link rel="stylesheet" type="text/css" href="style.css"&gt;
          &lt;script type="text/javascript" src="javascript.js"&gt;&lt;/script&gt;
      &lt;/head&gt;
      &lt;body&gt;
          &lt;div  id="container"&gt;
              &lt;div onclick="start()" id="topleft"&gt;&lt;/div&gt;
              &lt;div id="topright"&gt;&lt;/div&gt;
              &lt;div id="bottomleft"&gt;&lt;/div&gt;
              &lt;div id="bottomright"&gt;&lt;/div&gt;
          &lt;/div&gt;
  
      &lt;/body&gt;
  &lt;/html&gt;
  </code></pre>
  
  <p>CSS code</p>
  
  <pre><code>#container {
      width: 400px;
      height: 400px;
      background-color: red;
      margin: 0 auto;
      position: relative
  }
  #topright, #topleft,#bottomright, #bottomleft {
      width: 50px;
      height: 50px;
      background-color: black;
      position: absolute;
  }
  #bottomright, #bottomleft {
      bottom:0;/*175*/
  }
  #topright, #topleft {
      top:0; /*175*/
  }
  #bottomleft, #topleft {
      left:0; /*175*/
  }
  #bottomright, #topright {
      right:0; /*175*/
  }
  </code></pre>
  
  <p>JavaScript code</p>
  
  <pre><code>mt=0;
  function move(){
      topleft=document.getElementById("topleft");
      for (n=0;n&lt;=175;n++){
          topp=topleft.style.top;
          topp=parseInt(topp);
          topp++
          topleft.style.top=topp+"px"
      }
  }
  
  function start(){
      setInterval("move()",1);
  }
  </code></pre>
  
  <p>Can anybody rectify it?</p>