Printing out JSON array returned [closed]

Question

I have the following JSON array:

[{"occurences":"1","post_title":"Test 1","ID":"16"},    
 {"occurences":"1","post_title":"Test 2","ID":"19"},
 {"occurences":"1","post_title":"\u543b\u60a8\u7684\u5c41\u80a1","ID":"21"}] 

And I use this js to parse and print it:

success:function(data){
     $.each(data, function(i, post){
     content = '';
     content += '<li>' + post.post_title + '</li>';
   });

   $(content).appendTo("#search-results");

   }

But the display only showed "Undefined", and the Console showed no errors.

In case you ask, this is the HTML part:

<form id="search" action="">
<div class="toolbar">
    <h1>Search</h1>
    <a href="#" class="back">Back</a>
</div>
<ul class="rounded">
    <li><input type="text" name="search-text" placeholder="Search" id="search-text" /></li>
</ul>
<ul class="edgetoedge" id="search-results">
    <li class="sep">Results</li>                
</ul>
</form>

Any clue why? Many thanks in advance!