Display page name in javascript?

I would stick it in a function in case you need to reuse it elsewhere in your code. Just split the page name at the end and take the first element:

function getPageName(url) {
  return url.split('/').pop().split('.')[0];
}

You can pass in the actual URL:

var pageName = getPageName('www.example.com/whaterver/mypage.html'); // mypage

Or, using location.href:

var pageName = getPageName(location.href); // mypage

I might also be inclined to return something if there is no match for *.html, so here's a revised function that returns null if there isn't a match:

function getPageName(url) {
  var pageName = url.split('/').pop().split('.')[0];
  return pageName.length > 0 ? pageName : null;
}

DEMO

Note: If you do .split('.') like other solutions instruct, you will miss the base names from many URLs.

You can find the last forward slash and search ahead for the first ., ?, & or # to catch variations of URLs. This is the equivalent of PHP's basename

function getBaseName(url) {
  if(!url || (url && url.length === 0)) {
    return "";
  }
  var index = url.lastIndexOf("/") + 1;
  var filenameWithExtension = url.substr(index);
  var basename = filenameWithExtension.split(/[.?&#]+/)[0];

  // Handle '/mypage/' type paths
  if(basename.length === 0) {
    url = url.substr(0,index-1);
    basename = getBaseName(url);
  }
  return basename ? basename : ""; 
}

and use it like so

var url = "http://www.example.com/whaterver/mypage.html";
var file = getBaseName(url);

of

var file = getBaseName(location.pathname); // The current script page

Results:

http://www.example.com/whaterver/mypage/        =>  "mypage"
http://www.example.com/whaterver/mypage.html    =>  "mypage"  
http://www.example.com/whaterver/mypage         =>  "mypage"  
http://www.example.com/whaterver/mypage/        =>  "mypage"  
http://www.example.com/whaterver/mypage#works   =>  "mypage"  
http://www.example.com/whaterver/mypage?ver=1   =>  "mypage"

JSBin Demo