Use the below code
var value = $('td:first').html()
console.log(value)
to be more precise and for performance reasons, find within your table
var value = $('#table_id').find('td:first').html();
or
var value = $('#table_id').find('td').first().html();
btw.. your td elements should be within tr elements :) to make it as correct html markup.
If that is a plain string, you can get the value using
var value = $('<table>')append(
'<tr>'+your_html_string+'</tr>'
).find('td:first').html();