Jquery and Wordpress Json plugin - how do you get selected output from object?

Jquery and Wordpress Json plugin - how do you get selected output from object?

Sorry made a mess of my first post - here it is again.

Hi there, I'm hoping this is simple:
I'm using the Json plugin in a Wordpress blog, the below code spits out all the posts. Here it's showing the title and excerpt for each post (I can access the ID number too if I want). I'd like to just be able to display certain posts based on their ID. I hoped to use an if statement to select certain posts but it doesn't work - see my code at the very bottom.

Any help solving this would be appreciated.

function listPosts(data) {
    var output='<ul data-role="listview" data-filter="true">';
    $.each(data.posts,function(key,val) {
        output+='<li>';
        output+='<h3>' + val.title + '</h3>';
        output+='<p>' + val.excerpt + '</p>';
        output+='</li>';
    }); // go through each post
    output+='</ul>';
    $('#postlist').html(output);
} // lists all the posts

>>>>>>>>>>>>>>
MY ATTEMPT BELOW - doesn't work:

function listPosts(data) {
    var output='<ul data-role="listview" data-filter="true">';
    $.each(data.posts,function(key,val) {
        if (val.id['56']) && (val.id['61']){
        output+='<li>';
        output+='<h3>' + val.title + '</h3>';
        output+='<p>' + val.excerpt + '</p>';
        output+='</li>';
        }
    }); // go through each post
    output+='</ul>';
    $('#postlist').html(output);
} // lists all the posts