I am constructing an <li> element like this:

var element = $("<li></li>") 
    .html(mHTML)  
    .attr('id', "elemid");

I am trying to add this element to a <ul> element only if it doesn't already exist. Any ideas on how to do this? Am I supposed to use contains() to see if the ul element contain the html and then decide? For instance,

<ul id="elemul">
  <li id="elemli1">Element 1</li>
  <li id="elemli2">Element 2</li>
  <li id="elemli3">Element 3</li>
</ul>

If I try adding Element 1, it should not add it. What should I do if its a longer string (not really long but about 150 characters). Do I go about using hashmaps?