LUA_AT_CLIENT.lua51js.md

#Usage Examples

Here are some examples of Lua code that will run on the browser using the lua51js virtual machine:

##Hello World

<?lua@client

-- Log it to the console
print('hello' .. ' ' .. 'world!')

?>

##DOM Interaction

Currently, the lua51js mode can perform DOM interaction in limited ways.

For more advanced DOM manipulation, you will need to set a different VM such as starlight, moonshine or luavmjs.

<?lua@client
 js.document:write('Today is: '..os.date()..'<br>')
 js.document:write('Your User-Agent is: '..js.navigator.userAgent..'<br>')
 if js.navigator.cookieEnabled == true then
      js.document:write('Cookie support is enabled.<br>')
 else
      js.document:write('Cookie support is disabled.<br>')
 end
 
 function say_bye()
      js.document:write('Bye! :)')
 end
?>

<hr>

<?lua@client
 say_bye()
?>

##Both Client & Server Execution

<?lua@both
 msg = 'Houston, Tranquility Base here.'
 
 function getlastmsg()
  return 'The Eagle has landed.'
 end
?>

<h2><?=msg?></h2>
<h3><?=getlastmsg()?></h3>

<?lua@client
 js.window:alert(msg..' '..getlastmsg())
?>

##Calling JS functions from Lua

<?lua@client?><!-- Serve the VM first-->
<script type="text/javascript">
function myalert(L) {
 var str = C.luaL_checkstring(L, 1);
 window.alert(str);
 return 0;
}
LuaCS.addFunction('myalert',myalert);
</script>
<?lua@client
myalert('Hello World from Lua!')
?>

##Adding a Library

<?lua@client?><!-- Serve the VM first-->
<script type="text/javascript">
  var MyLib = {
   alert: function(L) {
    var str = C.luaL_checkstring(L, 1);
    window.alert(str);
    return 0;
   },
   upper: function(L) {
    var str = C.luaL_checkstring(L, 1);
    C.lua_pushstring(L,str.toUpperCase());
    return 1;
   }
  }
  
  var MyLibFuncs = [
   ["alert", MyLib.alert],
   ["upper", MyLib.upper]
  ];
  LuaCS.addLibrary("test", MyLibFuncs);
</script>
<?lua@client
  msg = test.upper('It works!')
  test.alert(msg)
?>

##Loading Lua Modules

Lua@Client can load Lua files and modules via a standard <script> tag. All that is needed is to edit the Apache httpd.conf file and add:

LuaMapHandler /pub/lua "path/to/lua/latclient/lp_handler.lua" provide_file

After this you can use a script tag pointing directly to files in the /pub/lua directory. Example:

<?lua@client?><!-- Serve the VM first-->
<script src="pub/lua/mymodule.lua"></script>

You will see that mymodule.lua is converted on-the-fly to JavaScript, extending the VM. Now you can load the library by just doing:

<?lua@client
require "pub.lua.mymodule"
...
?>

###On-the-fly Conversion Using CGI-Lua

To make a Lua file to provide itself as JS in CGI-Lua you can use:

if cgilua ~= nil then 
  p = require "latclient"
  p.cgilua_exit("/")
end

--[[Your Code Here]]

##Script Tag Support

<?lua@client?><!-- Serve the VM first-->
<script type="text/lua">
js.window:alert('Hello World from Lua!')
</script>

If you use this method, the Lua scripts will run after the page has loaded. For immediate execution, use the <?lua@client tag as explained above.

To-Do

• Some missing functions need to be implemented in lua5.1.js.
• Add a luaL_Reg wrapper.
• Replace the existing Lua<->JS bridge with a more advanced one, similar to the one included with lua.vm.js.
• Add a handler and file provider for Nginx.

Browser JS Objects

• navigator, history, screen, location (fully implemented)
• document, window, console (partially implemented)