JavaScript: Throttle requestAnimationFrame to maintain 30fps

One problem with using requestAnimationFrame is that rendering will take place as quickly as the computer can process the per-frame calculations and screen redraw. If you only want to run at 30fps, your computer might be running a lot faster than you want. To work around this problem, simply check the elapsed time before running the next frame update. Check out the example:

var frameLength = 33; // this is ~1/30th of a second, in milliseconds (1000/30)
var lastFrame = 0;

var render = function() {
  if(Date.now() - lastFrame > frameLength) {
    lastFrame = Date.now()

    // run your 30fps code here...
  }
  requestAnimationFrame(render);
};
requestAnimationFrame(render);

You'll notice that I'm using Date.now(), which requires a polyfill for old versions of IE. requestAnimationFrame also requires a polyfill for some browsers. Another solution is to use time-based calculations, but that's not always easy to implement.

Bookmarklet: Scrub through a Vine video

I was watching a friend's Vine video on the web, and I got the idea that it would be cool to control the playback of the video. I wrote this little bookmarklet to scrub through the video as you move your mouse over it. Here's the original JavaScript:

// grab video element and pause it
var vid = document.getElementById('post_html5_api'); 
vid.pause(); 
// get x offset of video
var vidX = 0; 
var el = vid;
while (el && !isNaN( el.offsetLeft ) && !isNaN( el.offsetTop ) ) {
  vidX += el.offsetLeft;
  el = el.offsetParent;
}
// scrub the video based on mouse x
var vidTime = vid.seekable.end(0); 
vid.addEventListener('mousemove', function(e) {
  var x = e.clientX - vidX;
  var percent = x / vid.offsetWidth;
  vid.currentTime = percent * vidTime;
}, false);

And the bookmarklet (Vine Scrubber):

javascript:(function()%7Bvar%20vid=document.getElementById('post_html5_api');vid.pause();var%20vidX=0;var%20el=vid;while(el&&!isNaN(el.offsetLeft)&&!isNaN(el.offsetTop))%7BvidX+=el.offsetLeft;el=el.offsetParent;%7Dvar%20vidTime=vid.seekable.end(0);vid.addEventListener('mousemove',function(e)%7Bvar%20x=e.clientX-vidX;var%20percent=x/vid.offsetWidth;vid.currentTime=percent*vidTime;%7D,false)%7D)();

Bookmarklet: Select & invite all friends on Facebook

This may be an evil thing, as I hate getting unwanted invites and spam on Facebook... But if you're throwing an event or have created a Facebook "Page", you might want to invite a bunch of people. You probably don't want to have to click each person's name/picture to add them to the invite, so I wrote a little bookmarklet to select them all at once. Simply scroll down to the bottom of your list of friends (it will load more in as you scroll). Once your (no-longer) friends have all loaded, click the bookmarklet to check them all. Here's the original code:

var checks = document.getElementsByClassName('checkableListItem');
for(i=0; i<checks.length; i++){ $(checks[i]).click(); }

And the same code, reformatted for a bookmarklet:

javascript:(function()%7Bvar checks%3Ddocument.getElementsByClassName(%27checkableListItem%27)%3Bfor(i%3D0%3Bi<checks.length%3Bi%2B%2B)%7B%24(checks%5Bi%5D).click()%3B%7D%7D)()%3B

I shall pay for this with spam karma.

JavaScript: Use the goo.gl link shortener from your own site

Here's a quick, stripped-down version of a javascript implementation of the goo.gl link-shortener service. It asynchronously loads the Google client API, then uses another callback when the link shortener service is loaded. After the service loads, you can call shortenUrl() as many times as you'd like. For simplicity, I've only shortened one URL here. It doesn't appear that you need an API key to simply shorten URLs, but certain calls to this service would require one. Here's the basic version, which should work in modern browsers.

var shortenUrl = function() {
  var request = gapi.client.urlshortener.url.insert({
    resource: {
      longUrl: 'http://plasticsoundsupply.com'
    }
  });
  request.execute(function(response) {
    var shortUrl = response.id;
    console.log('short url:', shortUrl);
  });
};

var googleApiLoaded = function() {
  // gapi.client.setApiKey("YOUR API KEY")
  gapi.client.load("urlshortener", "v1", shortenUrl);
};

window.googleApiLoaded = googleApiLoaded;
$(document.body).append('<script src="https://apis.google.com/js/client.js?onload=googleApiLoaded"></script>');

JavaScript: Antialias post-processing with THREE.js on a (non) retina screen

When drawing a basic Mesh object in THREE.js, the edges can be particularly jagged if your browser doesn't properly support antialiasing in webGL (most don't seem to at the moment). In my current project this became a sticking point, and I set out to fix the aliased edges of my 3D models and Mesh objects.

I found the FXAA post-processing shader effect in the THREE.js library, and it worked like a charm to smooth the rough edges. However, the THREE.EffectComposer utility doesn't automatically handle different pixel densities, and by default, the aliasing actually became twice as bad on the Retina screen of my Mac. After some fiddling, I found that you simply have to adjust the uniforms for the shader effect if it depends on knowing your screen size, as well as set the screen size for the EffectsComposer object.

See below, where I detect the pixel density, and use that to multiply your screen dimensions in the shader and EffectComposer:

var composer, dpr, effectFXAA, renderScene;

dpr = 1;
if (window.devicePixelRatio !== undefined) {
  dpr = window.devicePixelRatio;
}

renderScene = new THREE.RenderPass(scene, camera);
effectFXAA = new THREE.ShaderPass(THREE.FXAAShader);
effectFXAA.uniforms['resolution'].value.set(1 / (window.innerWidth * dpr), 1 / (window.innerHeight * dpr));
effectFXAA.renderToScreen = true;

composer = new THREE.EffectComposer(renderer);
composer.setSize(window.innerWidth * dpr, window.innerHeight * dpr);
composer.addPass(renderScene);
composer.addPass(effectFXAA);

You'll also probably want to update these settings if the window size changes, like so:

$(window).on('resize', onWindowResize);

function onWindowResize(e) {
  effectFXAA.uniforms['resolution'].value.set(1 / (window.innerWidth * dpr), 1 / (window.innerHeight * dpr));
  composer.setSize(window.innerWidth * dpr, window.innerHeight * dpr);
}