Niels Leenheer
@html5test.com
CTO of Salonhub. Creator of http://html5test.com, writes at http://nielsleenheer.com, team @FronteersConf, Google Developers Expert, Invite me to speak at your event.
Just got home. First thing my 11-year old said to me: Dad, did you buy a flamethrower…?
Eh. Yes. Yes, I did. 🔥
Eh. Yes. Yes, I did. 🔥
November 8, 2025 at 3:31 PM
Just got home. First thing my 11-year old said to me: Dad, did you buy a flamethrower…?
Eh. Yes. Yes, I did. 🔥
Eh. Yes. Yes, I did. 🔥
@nerdy.dev This is happening. MIDI → CSS → DMX → 🔥
November 8, 2025 at 10:03 AM
@nerdy.dev This is happening. MIDI → CSS → DMX → 🔥
Looking for some random thing on AliExpress when suddenly… Hey! I could use a flame thrower! It would be fun to connect it to the web and…
November 5, 2025 at 10:02 AM
Looking for some random thing on AliExpress when suddenly… Hey! I could use a flame thrower! It would be fun to connect it to the web and…
And from London to Warsaw where I will join DevFest Warsaw and give a talk about Project Fugu.
I will show how my company build a completely browser based cash register application that is using WebUSB, WebHID, WebSerial for talking to point of sale devices.
🎟️ sites.google.com/view/devfest...
I will show how my company build a completely browser based cash register application that is using WebUSB, WebHID, WebSerial for talking to point of sale devices.
🎟️ sites.google.com/view/devfest...
November 4, 2025 at 1:43 PM
And from London to Warsaw where I will join DevFest Warsaw and give a talk about Project Fugu.
I will show how my company build a completely browser based cash register application that is using WebUSB, WebHID, WebSerial for talking to point of sale devices.
🎟️ sites.google.com/view/devfest...
I will show how my company build a completely browser based cash register application that is using WebUSB, WebHID, WebSerial for talking to point of sale devices.
🎟️ sites.google.com/view/devfest...
Only two more weeks until it is time for HalfStack London. Attending HalfStack is always a treat with great talks, fun people and good pizza.
I'll be speaking again this year about Baseline and how we can make informed choices about browser support in 2025.
🎟️ halfstackconf.com/london
I'll be speaking again this year about Baseline and how we can make informed choices about browser support in 2025.
🎟️ halfstackconf.com/london
October 29, 2025 at 11:08 AM
Only two more weeks until it is time for HalfStack London. Attending HalfStack is always a treat with great talks, fun people and good pizza.
I'll be speaking again this year about Baseline and how we can make informed choices about browser support in 2025.
🎟️ halfstackconf.com/london
I'll be speaking again this year about Baseline and how we can make informed choices about browser support in 2025.
🎟️ halfstackconf.com/london
So did I spend this Sunday building a gravity simulation for the hands of the clock? Kind of... yeah. Eventually this will run on an Pi with a 5" circular screen and a sensor hat.
Is it useful? No. But it was fun and it is just amazing to see what the web platform is capable of.
Is it useful? No. But it was fun and it is just amazing to see what the web platform is capable of.
October 27, 2025 at 8:53 AM
So did I spend this Sunday building a gravity simulation for the hands of the clock? Kind of... yeah. Eventually this will run on an Pi with a 5" circular screen and a sensor hat.
Is it useful? No. But it was fun and it is just amazing to see what the web platform is capable of.
Is it useful? No. But it was fun and it is just amazing to see what the web platform is capable of.
Another new experiment: a clock.
A great clock because it doesn't care how you hold it. It levels itself.
A bad clock, because it breaks easily. Shake it and the hands will drop down by gravity.
The best part... you can set the time by just moving the hands and give them a little sweep.
A great clock because it doesn't care how you hold it. It levels itself.
A bad clock, because it breaks easily. Shake it and the hands will drop down by gravity.
The best part... you can set the time by just moving the hands and give them a little sweep.
October 27, 2025 at 8:47 AM
Another new experiment: a clock.
A great clock because it doesn't care how you hold it. It levels itself.
A bad clock, because it breaks easily. Shake it and the hands will drop down by gravity.
The best part... you can set the time by just moving the hands and give them a little sweep.
A great clock because it doesn't care how you hold it. It levels itself.
A bad clock, because it breaks easily. Shake it and the hands will drop down by gravity.
The best part... you can set the time by just moving the hands and give them a little sweep.
New scope! Well… it’s an old scope and it is in pretty terrible state. But at least it is working. Hasn’t blown a capacitor yet.
And look! SVG paths!
The principles are actually really simple. I’ll do a write up at a later moment.
And look! SVG paths!
The principles are actually really simple. I’ll do a write up at a later moment.
October 26, 2025 at 10:04 PM
New scope! Well… it’s an old scope and it is in pretty terrible state. But at least it is working. Hasn’t blown a capacitor yet.
And look! SVG paths!
The principles are actually really simple. I’ll do a write up at a later moment.
And look! SVG paths!
The principles are actually really simple. I’ll do a write up at a later moment.
And the oscilloscope just went up in smoke 💨
A crackling sound. A huge puff of white smoke. Scrambling to find the power cable and just caught the last bit on camera. One might think we have a new pope.
A crackling sound. A huge puff of white smoke. Scrambling to find the power cable and just caught the last bit on camera. One might think we have a new pope.
October 25, 2025 at 6:42 PM
And the oscilloscope just went up in smoke 💨
A crackling sound. A huge puff of white smoke. Scrambling to find the power cable and just caught the last bit on camera. One might think we have a new pope.
A crackling sound. A huge puff of white smoke. Scrambling to find the power cable and just caught the last bit on camera. One might think we have a new pope.
I bought an old, second hand oscilloscope and made something cool.
I’m using WebAudio to send separate signals to the left and right channel. Feed those into the BNC inputs of the oscilloscope. Plot it on the X and Y axis. And you can make arbitrary line drawings.
I’m using WebAudio to send separate signals to the left and right channel. Feed those into the BNC inputs of the oscilloscope. Plot it on the X and Y axis. And you can make arbitrary line drawings.
October 25, 2025 at 3:49 PM
I bought an old, second hand oscilloscope and made something cool.
I’m using WebAudio to send separate signals to the left and right channel. Feed those into the BNC inputs of the oscilloscope. Plot it on the X and Y axis. And you can make arbitrary line drawings.
I’m using WebAudio to send separate signals to the left and right channel. Feed those into the BNC inputs of the oscilloscope. Plot it on the X and Y axis. And you can make arbitrary line drawings.
I am afraid this is turning into an addiction. I just bought tickets for a flight to Tromsø for another Northern Lights trip expedition… 😬
October 11, 2025 at 2:07 PM
I am afraid this is turning into an addiction. I just bought tickets for a flight to Tromsø for another Northern Lights trip expedition… 😬
Yes!
I use this in one of my talks about the resilience of HTML. It's a joke, but also to point out that very little just is removed from the web platform. Yes, marque may be "deprecated" or "obsolete", it is still part of the standard and works in browsers.
Now <blink> on the other hand...
I use this in one of my talks about the resilience of HTML. It's a joke, but also to point out that very little just is removed from the web platform. Yes, marque may be "deprecated" or "obsolete", it is still part of the standard and works in browsers.
Now <blink> on the other hand...
October 7, 2025 at 11:16 AM
Yes!
I use this in one of my talks about the resilience of HTML. It's a joke, but also to point out that very little just is removed from the web platform. Yes, marque may be "deprecated" or "obsolete", it is still part of the standard and works in browsers.
Now <blink> on the other hand...
I use this in one of my talks about the resilience of HTML. It's a joke, but also to point out that very little just is removed from the web platform. Yes, marque may be "deprecated" or "obsolete", it is still part of the standard and works in browsers.
Now <blink> on the other hand...
Playing around with CSS Anchor Positioning in Safari 26... And it is not going well..
October 6, 2025 at 8:44 AM
Playing around with CSS Anchor Positioning in Safari 26... And it is not going well..
Not much hope for Liquid Glass improvements in iOS 26.1…
September 27, 2025 at 1:43 PM
Not much hope for Liquid Glass improvements in iOS 26.1…
My very first talk is more than 10 years ago. I was so nervous that I felt sick. But when I finally stood on that stage and started talking that all went away and I really enjoyed it. Never thought I would be able to do that.
September 2, 2025 at 5:56 PM
My very first talk is more than 10 years ago. I was so nervous that I felt sick. But when I finally stood on that stage and started talking that all went away and I really enjoyed it. Never thought I would be able to do that.
How many unread mails? According to Liquid Glass it is…. Gray text on top of other gray blurry text.
August 17, 2025 at 6:52 AM
How many unread mails? According to Liquid Glass it is…. Gray text on top of other gray blurry text.
And these are not exceptions. This is all over the place.
Guess what this button does? Is is enabled or disabled. Nobody knows.
It is a checkmark to confirm the photo selection in Photos and it is enabled.
Guess what this button does? Is is enabled or disabled. Nobody knows.
It is a checkmark to confirm the photo selection in Photos and it is enabled.
August 14, 2025 at 9:59 AM
And these are not exceptions. This is all over the place.
Guess what this button does? Is is enabled or disabled. Nobody knows.
It is a checkmark to confirm the photo selection in Photos and it is enabled.
Guess what this button does? Is is enabled or disabled. Nobody knows.
It is a checkmark to confirm the photo selection in Photos and it is enabled.
Liquid Glass will automatically ensure that there is enough contrast between buttons and background promised Apple.
The reality:
The reality:
August 14, 2025 at 9:54 AM
Liquid Glass will automatically ensure that there is enough contrast between buttons and background promised Apple.
The reality:
The reality:
Ah yes. The motto of Liquid Glass: Form over function. Why should we care about readability and usability? We’ve made everything pretty. That is all that matters, right?
August 12, 2025 at 2:51 PM
Ah yes. The motto of Liquid Glass: Form over function. Why should we care about readability and usability? We’ve made everything pretty. That is all that matters, right?
Does the text here have enough contrast?
Liquid Glass on iOS 26:
Great! Ship it!
Liquid Glass on iOS 26:
Great! Ship it!
August 12, 2025 at 2:31 PM
Does the text here have enough contrast?
Liquid Glass on iOS 26:
Great! Ship it!
Liquid Glass on iOS 26:
Great! Ship it!
When your eleven year old son tries to be funny.
August 10, 2025 at 7:35 PM
When your eleven year old son tries to be funny.
A week or two ago, MDN turned 20 years old 🎉
developer.mozilla.org/en-US/blog/m...
So I went back into my archives from 20 years ago to find the designs I created for the very first version of MDN. It's so weird to look at this again 20 years later.
@developer.mozilla.org
developer.mozilla.org/en-US/blog/m...
So I went back into my archives from 20 years ago to find the designs I created for the very first version of MDN. It's so weird to look at this again 20 years later.
@developer.mozilla.org
August 10, 2025 at 11:01 AM
A week or two ago, MDN turned 20 years old 🎉
developer.mozilla.org/en-US/blog/m...
So I went back into my archives from 20 years ago to find the designs I created for the very first version of MDN. It's so weird to look at this again 20 years later.
@developer.mozilla.org
developer.mozilla.org/en-US/blog/m...
So I went back into my archives from 20 years ago to find the designs I created for the very first version of MDN. It's so weird to look at this again 20 years later.
@developer.mozilla.org
Not only cool swag today at #GoogleIOConnect, but also some great talks about new web platform features. Interesting day.
June 25, 2025 at 3:11 PM
Not only cool swag today at #GoogleIOConnect, but also some great talks about new web platform features. Interesting day.
Having a lovely offline-dinosaur ice cream popsicle. Dinos taste like mango. #GoogleIOConnect
June 25, 2025 at 2:20 PM
Having a lovely offline-dinosaur ice cream popsicle. Dinos taste like mango. #GoogleIOConnect
Funny how I have the same pictures at approximately the same time from the other side of the earth…
June 19, 2025 at 4:08 PM
Funny how I have the same pictures at approximately the same time from the other side of the earth…