var obj_array:Array = new Array();
obj_array.push({Name:"aaa", Value:1});
obj_array.push({Name:"bbb", Value:2});
obj_array.push({Name:"ccc", Value:3});

getValue("aaa", obj_array);
function getValue(str:String, ary:Array):Number
{
    var nLoop:Number = ary.length;
    for ( var i:Number = 0; i < nLoop; i++ )
    {
       if ( ary[i].Name == str )
       {
          return ary[i].Value;
       }
    }

    return -1;
}

getValue("aaa", obj_array, "Name", "Value");
function getValue(str:String, ary:Array, strID:String, strTarget):Number
{
    var nLoop:Number = ary.length;
    for ( var i:Number = 0; i < nLoop; i++ )
    {
       if ( ary[i][strID] == str )
       {
          return ary[i][strTarget];
       }
    }

    return -1;
}