Snippets

These snippets are my attempt to save and organize various bits of code, best practices, and resources relating to web development and design. They also function as a to do list of sorts, for things I want to implement in my own code, but haven't yet. The concept is inspired by Jeremy Keith's links and CSS-Tricks, among other things. Enjoy.

Send messages when you’re back online with Service Workers and Background Sync

This example of using background sync looks like it’s specific to Twilio, but the breakdown of steps is broad enough to apply to many situations:

On the page we need to:

  1. Register a Service Worker
  2. Intercept the “submit” event for our message form
  3. Place the message details into IndexedDB, an in browser database
  4. Register the Service Worker to receive a “sync” event

Then, in the Service Worker we need to:

  1. Listen for sync events
  2. When a sync event is received, retrieve the messages from IndexedDB
  3. For each message, send a request to our server to send the message
  4. If the message is sent successfully, then remove the message from IndexedDB

And that’s it.

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Understanding the Critical Rendering Path

A visual representation of the critical rendering path. See text following image.

When a browser receives the HTML response for a page from the server, there are a lot of steps to be taken before pixels are drawn on the screen. This sequence the browsers needs to run through for the initial paint of the page is called the "Critical Rendering Path".

Knowledge of the CRP is incredibly useful for understanding how a site's performance can be improved. There are 6 stages to the CRP -

  1. Constructing the DOM Tree
  2. Constructing the CSSOM Tree
  3. Running JavaScript
  4. Creating the Render Tree
  5. Generating the Layout
  6. Painting

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Transparent JPG (With SVG)

This is really excellent: take a JPG, which has great compression for photos, but doesn't support transparency, and link it within an <svg> which can apply a clipping mask based on a path. The path can be traced manually over the photo in Photoshop or Illustrator, and can be exported as an SVG file from Illustrator. The following code (minus the path data), demonstrates how to do this:

HTML

<svg viewBox="0 0 921.17 1409.71">
  <defs>
    <clipPath id="chris-clip">
      <path d=" ... " />
    </clipPath>
  </defs>
  <image xlink:href="/images/chris.jpg" clip-path="url(#chris-clip)" x="0" y="0" width="921" height="1409">
<svg>

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