How to retrieve ListItem.Value and ListItem.Text of vb.NET by JavaScript?

Hello, I have arrayList of ListItem which has different Text and Value.
such as {{James Dean, 123}, {Bruce Lee, 456}}
I bound the arrayList to a ListBox1.
The ListBox displays only James Dean and Bruce Lee.
How can I retrieve the Value by using javascript?
I tried as;
var source = document.getElementById('ListBox1');
var dest = document.getElementById('TextBox1');

var finalText = '';
for (var x=0; x<source.options.length; x++)
{
if (source.options[x].text != '')
{
finalText += source.options[x].text + " ";
finalText += source.options[x].value + ",";
}
}

dest.value = shadowText;

I expected to see both Texts and Values, however, the TextBox1 displayed 'James Dean James Dean, Bruce Lee Bruce Lee'.

How can I get the string 'James Dean 123, Bruce Lee 456' by using javascript?

Thanks in advance