What it really means is we are pressing an button which sends an argument threw the URL and based on the URL we change a drop-down list.

So for example we have a button like this

<a class=”Button” href=”/another-page/?field8_4=1″>Button</a>

This button goes to a page and sends 2 arguments the field8_4 and the field number i this case the first (1).

The script in the other hand just takes this information and changes the drop-down field based on the argument.

var params = window.location.search.substr(1).split(‘=’);
if(params.length > 1){

jQuery(‘#fscf_field8_4 option[value=”‘ + params[1] +'”]’).attr(‘selected’, ‘selected’);

so it looks for the field8_4 then, get a “params” variable where it stores the location of the subscript and splits it with the “=” sign.

The if statement just makes sure that there are more then one parameter sent, and if so get the value of the params and select the field based on the param.