Using a variable as part of a javascript array

I have an object (that I can change!) that looks like this:

var pageContent = {
    "contact_us":[{
        "content":"<p>Lots of content here.</p>",
        "title":"Contact Us"
     }],
    "index":[{
        "content":"<p>Some other content here.</p>",
        "title":"Home Page"
     }],
    "gallery":[{
        "content":"<p>Some mo开发者_JAVA技巧re content</p>",
        "title":"Gallery"
     }],
 }

To access properties, I'm doing this:

pageContent.gallery[0]['title'];

To get the value "Gallery".

What I want to do is something like this:

var newPage = "gallery";
pageContent.newpage[0]['title'];

But, obviously that fails. How can I do what I want? Changes to anything are welcome, nothing is set in stone here.

You can use square bracket notation, like this:

var title = pageContent[newpage][0]['title'];