how to create controls dynamically using javascript

Question

Dear All,

I need to create Controls Dynamically & place them into table..

<table>
<tr><td>Some info</td>
<td>Textbox</td>
<td>Add Button for adding textbox</td>
<td>other info</td></tr>
---------Control place----------
<tr><td>some info</td>
<td>Textbox</td>
<td>Add Button for adding textbox</td>
<td>other info</td></tr>

</table>

so my requirement is when i click Add Button then in the place of Control place in above scenario it have to create one row (<tr>) & I need to place my control in that location & the Add Button have to come beside of new textbox..

as follows.

<table>
<tr><td>Some info</td>
<td>Old Textbox</td>
<td>blank(null)</td>
<td>other info</td></tr>

<tr><td>Some info</td>
<td>New Textbox</td>
<td>Add Button</td>
<td>Other info</td></tr>

<tr><td>Some info</td>
<td>Textbox</td>
<td>Add Button for adding textbox</td>
<td>other info</td></tr>

</table>

Again if i click Add button Again i have to same process..

How can i do this using Javascript