slice JSON string
===

I have fetch data from mysql and echo a json encode as follow

    enter code here

    $result = mysql_query ("SELECT * FROM order_list");
    $myjsons = array();
    $i = 0;
    while ($row = mysql_fetch_assoc($result)) {
        $myjsons[$i] = json_encode(array($row));
        $i++;
    }
    echo json_encode($myjsons);
and I have a javascript function that reads the string and show it in a text box


    enter code here
    if(ajaxRequest.readyState == 4){
    $.post('userfind.php', function(data) {
        $("#txtfld").val(data);

        var arr =data.slice(1);
        var user_arr = arr.slice(0,-1);
        var json = user_arr,
        obj = JSON.parse(json);
        alert(obj.user_id);

        $("#resultTXT").val(obj.user_id);


        },'json'

        );		}
	}
	ajaxRequest.open("POST", "userfind.php", true);
	ajaxRequest.send(null); 
        }

the problem is that txtfld shows  the string as [{"user_id":"2790","fre.....tst":""}]

and resultTXT shows nothing because of two [ ]

I have tried to remove them using slice but it seems that the slice doesn't effect on JSON string. 

Whatelse can i do to remove [ ] so the resultTXT shows the user_id ?

Thanks