[Solved] How do I add a table row to a table after the forth using Javascript and or jQuery? [closed]

Try :eq() and .after()

$('table tr:eq(3)').after('<tr><td>5</td></tr>');

fiddle Demo

or

.insertAfter()

$('<tr><td>5</td></tr>').insertAfter('table tr:eq(3)');

fiddle Demo