Engineer at Facebook and GDE in Web Techologies. Ex Spotify.
tl;dr: Communication between an iframe and a popup is not straightforward. If you are implementing a widget-ish element that needs to communicate with other page, Have a read at this (and test your solution on multiple platforms).
This article explains some ideas behind a small project to detect the tempo of a song using the Audio API. I recommend you to have a look at these links before reading the rest of the article: Demo and Code on GitHub. 
It’s been a few weeks since I last posted. Rather than being on vacations resting on a beach, I have be been busy trying out some things I had in my backlog, and one of them is Polymer. Read below about what Polymer is and my impressions after creating some elements.
I have just come across the post Improve the payment experience with animations - Behind the scenes of Stripe Checkout. I must say that I don’t usually take into account animations when building a UI, since the priority is always the layout and I seldom have time to enhance the interface with subtle animations.
After reading the article one starts appreciating those transitions that became a thing when the iPhone went out (maybe too much on iOS7?. The good thing is that good animations make the interface look smoother and more professional, and it just feels great to use it. However, it is very easy to end up overusing animations and applying them to lots of elements just because it is possible.
I have attended many meetups since I arrived in Stockholm almost 2 years ago. The ones I like the most are those that deal with real situations and experience from startups and other companies.
It’s been some time since my previous post and I wanted to write a short one telling what has been going on.
I have several small personal projects around Spotify in which I am working in my free time. I recently attended the Music Hack Day Paris 2014, where I coded Spotify iQuiz, an iQuiz-like web app that uses your Spotify playlists and to create some questions about albums and tracks you saved. I think the most fun part is the Speech Synthesis API, which provides a very easy to use text-to-voice feature, right on your browser.
Yesterday I attended a meetup by Meteor Stockholm in which there were some talks and a short hack event. 
We have just finished the second edition of the Spotify Hack Week. Like the previous one, the whole company has been hacking for a whole week lots of different projects. We have played with Raspberry Pi, 3D printers, and even stationary bicycles.
A few weeks ago I migrated this blog to Jekyll and GitHub Pages, and the process has turned out to be quite easy. I have wanted to give Octopress or Jekyll a try for a long time, but I never found the time.
WordPress is a powerful blogging platform. I have used it for a 3 years to serve the few posts I have written so far. But I felt I wasn’t really using many of its features and I wanted to use a Markdown to compose and store my posts.
I like Grunt.js. Since I started using it I have applied it to all my web projects. It has improved my workflow by providing a uniform way to perform operations such as combination of files, minification, optimization and testing, to name a few. And I already posted about it when I talked about how to make Javascript more testable.
Grunt made it a non-brainer thing to carry out tasks that were more cumbersome to setup before. More often than not I would not dare to clone a repo and give it a try, if I had to set up many dependencies. Now I feel relieved when I see it contains a Gruntfile.js file.