Question

<ul id="list">
<li><input name="int[]" type="checkbox" value="1" id="int1" />int1</li>
<li><input name="int[]" type="checkbox" value="2" id="int2" />int2</li>
<li><input name="int[]" type="checkbox" value="3" id="int3" />int3</li>
<li><input name="int[]" type="checkbox" value="4" id="int4" />int4</li>
</ul> 

this

$("#list").append('<li><input name="int[]" type="checkbox" value="55" id="int55" />int55</li>');

make:

<ul id="list">
<li><input name="int[]" type="checkbox" value="1" id="int1" />int1</li>
<li><input name="int[]" type="checkbox" value="2" id="int2" />int2</li>
<li><input name="int[]" type="checkbox" value="3" id="int3" />int3</li>
<li><input name="int[]" type="checkbox" value="4" id="int4" />int4</li>
<li><input name="int[]" type="checkbox" value="55" id="int55" />int55</li>
</ul> 

how can i make for example

<ul id="list">
<li><input name="int[]" type="checkbox" value="1" id="int1" />int1</li>
<li><input name="int[]" type="checkbox" value="2" id="int2" />int2</li>
<li><input name="int[]" type="checkbox" value="55" id="int55" />int55</li>
<li><input name="int[]" type="checkbox" value="3" id="int3" />int3</li>
<li><input name="int[]" type="checkbox" value="4" id="int4" />int4</li>
</ul> 

or

<ul id="list">
<li><input name="int[]" type="checkbox" value="1" id="int1" />int1</li>
<li><input name="int[]" type="checkbox" value="2" id="int2" />int2</li>
<li><input name="int[]" type="checkbox" value="3" id="int3" />int3</li>
<li><input name="int[]" type="checkbox" value="55" id="int55" />int55</li>
<li><input name="int[]" type="checkbox" value="4" id="int4" />int4</li>
</ul> 

?

Answer 1

Selectors in jquery are realy powerful

 $("#list > li:eq(2)").after('<li><input name="int[]" type="checkbox" value="55" id="int55" />int55</li>');