One neat discovery I found in the webOS 1.4.5 SDK is that it is possible to have a simple app which doesn’t use Mojo. Why would you want to? Load time! Mojo brings a lot to the table, but if you want to use your own favorite JavaScript framework, much of that ends up being overhead and increases your app’s load time.
Step one: Make a web app and test it in Chrome or Safari.
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01//EN"
"http://www.w3.org/TR/html4/strict.dtd">
<html lang="en">
<head>
<title>Hello</title>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
</head>
<body>
<h1>Hello World!</h1>
</body>
</html>
Save this into a new folder (using a folder name of “hello” in this example) as index.html. This will become your app folder. You can test your app in Chrome or Safari by simply opening this file in your browser. Not terribly impressive, but hey, it’s a start.
Step two: Add a file to turn your folder into an app.
{
"id":"com.yourdomain.hello",
"version":"0.0.1",
"vendor":"Your Company",
"type":"web",
"main":"index.html",
"title":"Hello"
}
Save this off as appinfo.json in your application folder. You can test this app real fast in webOS. Just pull up your emulator, then open a command line prompt and do this:
palm-package hello palm-install com.yourdomain.hello_0.0.1_all.ipk
Then go to your emulator and pull it up. And… nothing happens. You get a blank card and a loading spinner. Hypnotic, but certainly not what we intended. We’re missing something, and luckily it’s not much of a something.
Step three: Add this tiny chunk of JavaScript near the top:
if (window.PalmSystem) PalmSystem.stageReady();
This tells webOS that you are ready to present your app to the user. It exists to give you a chance to preload whatever you need (usually your JavaScript libraries and some app initialization) so your users don’t see things flying around the screen as you load them.
Add that line of code, so now your index.html should look like this:
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01//EN"
"http://www.w3.org/TR/html4/strict.dtd">
<html lang="en">
<head>
<title>Hello</title>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
</head>
<body>
<script>
if (window.PalmSystem)
window.PalmSystem.stageReady();
</script>
<h1>Hello World!</h1>
</body>
</html>
Now when you palm-package and palm-install (as above) and then run your app, instead of a card floating there with a loading spinner, you get your app!
Moving forward
From here, you can add your favorite JavaScript library (some work better on mobile devices than others), and make a proper app.
This is exciting stuff for cross platform mobile development. I’ll be working closely with Palm engineering to see what other gems we can expose, so stay tuned!
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Great, I tried it in my project and it works. So now we can delete
from our index.html.
Do you know if it is possible to set landscape mode when using your trick above?
Right now I get landscape mode by setting:
this.controller.setWindowOrientation(‘left’);
in stage-assistant.js, and that ofcourse does not work when you leave out the Mojo include.
Above should say,
So now we can delete the Mojo include from out index.html
Not yet, but I’m working on that and a few other common tasks. Stay tuned.
I’ve been working on the same experiment. My experiment is here http://developer.palm.com/appredirect/?packageid=com.creationix.canvasclock
Source code is mentioned in the description.
Wow I just grabed some random open source tictactoe game and paste it in index.html and this works flawlessly using your trick. wow!! it launches instantly too! did’nt realize that mojo was the main culprit behind the slow webOS launches, no wonder the pdk apps launches so fast. I can now see how Enyo would speed things up!