An easier way of using polyfills
hacks.mozilla.org
An easier way of using polyfills
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Re: An easier way of using polyfills
#2While a neat idea in theory, I have some qualms about this. User agent detection sounds great, until you have a user that spoofs their agent. I often do so for various reasons, and from time to time I forget to turn it off after I've finished what I was doing.
If this service becomes common, then I will be given broken webpages seemingly at random. The other option, a polyfill covering specific features and served to all clients, regardless of user agent, doesn't suffer from that.
Re: An easier way of using polyfills
#3While a neat idea in theory, I have some qualms about this. User agent detection sounds great, until you have a user that spoofs their agent. I often do so for various reasons, and from time to time I forget to turn it off after I've finished what I was doing. If this service becomes common, then I will be given broken webpages seemingly at random. The other option, a polyfill covering specific features and served to…
>User agent detection sounds great, until you have a user that spoofs their agent.
Do a significant percentage of users spoof their agent?
Re: An easier way of using polyfills
#4While a neat idea in theory, I have some qualms about this. User agent detection sounds great, until you have a user that spoofs their agent. I often do so for various reasons, and from time to time I forget to turn it off after I've finished what I was doing. If this service becomes common, then I will be given broken webpages seemingly at random. The other option, a polyfill covering specific features and served to…
Polyfills won't break your page and random, worse case you get worse performance over native. However the point of a polyfill is to do exactly what the native method would have done if it existed
Re: An easier way of using polyfills
#5While a neat idea in theory, I have some qualms about this. User agent detection sounds great, until you have a user that spoofs their agent. I often do so for various reasons, and from time to time I forget to turn it off after I've finished what I was doing. If this service becomes common, then I will be given broken webpages seemingly at random. The other option, a polyfill covering specific features and served to…
Users that spoof their user agent are likely to either be tech-savvy people who either know what they are doing or who are hiding who they are, like a bot.
I'm more worried about supporting older users on old machines who barely know the difference between Internet Explorer and the internet than in supporting someone who knows exactly what a UA is and how to spoof it.
Re: An easier way of using polyfills
#6While a neat idea in theory, I have some qualms about this. User agent detection sounds great, until you have a user that spoofs their agent. I often do so for various reasons, and from time to time I forget to turn it off after I've finished what I was doing. If this service becomes common, then I will be given broken webpages seemingly at random. The other option, a polyfill covering specific features and served to…
Most JavaScript polyfills first check if the native implementation exists, and only if it doesn't the polyfill is activated. This shouldn't break anything. However, the blog article states they use User-Agent detection over feature detection. I hope they combine these solutions.
Re: An easier way of using polyfills
#7While a neat idea in theory, I have some qualms about this. User agent detection sounds great, until you have a user that spoofs their agent. I often do so for various reasons, and from time to time I forget to turn it off after I've finished what I was doing. If this service becomes common, then I will be given broken webpages seemingly at random. The other option, a polyfill covering specific features and served to…
Most JavaScript polyfills first check if the native implementation exists, and only if it doesn't the polyfill is activated. This shouldn't break anything. However, the blog article states they use User-Agent detection over feature detection. I hope they combine these solutions.
You can't use feature detection with a simple script tag. It's calling in a script and the cdn chooses the file to send based on the user-agent. No Javascript is run that would allow it to feature detect before choosing to send the load. There may be feature detection afterwards of course.
Re: An easier way of using polyfills
#8While a neat idea in theory, I have some qualms about this. User agent detection sounds great, until you have a user that spoofs their agent. I often do so for various reasons, and from time to time I forget to turn it off after I've finished what I was doing. If this service becomes common, then I will be given broken webpages seemingly at random. The other option, a polyfill covering specific features and served to…
Polyfills won't break your page and random, worse case you get worse performance over native. However the point of a polyfill is to do exactly what the native method would have done if it existed
Yes but the way mozilla has chosen to implement this is to send the code over the wire based on the clients UA. So if a method doesn't exist that should exist the client will never receive it.
It would be cool if they allowed you to disable this feature, and just use feature detection and always load the code for the requested item.
Re: An easier way of using polyfills
#9Earlier quoted context omitted.
Most JavaScript polyfills first check if the native implementation exists, and only if it doesn't the polyfill is activated. This shouldn't break anything. However, the blog article states they use User-Agent detection over feature detection. I hope they combine these solutions.
You can't use feature detection with a simple script tag. It's calling in a script and the cdn chooses the file to send based on the user-agent. No Javascript is run that would allow it to feature detect before choosing to send the load. There may be feature detection afterwards of course.
While the roundabout trip would be a waste, it shouldn't be hard to just include a quick and simple feature detection before the polyfill is injected. I don't see any reason why one wouldn't do it.
Re: An easier way of using polyfills
#10Earlier quoted context omitted.
Most JavaScript polyfills first check if the native implementation exists, and only if it doesn't the polyfill is activated. This shouldn't break anything. However, the blog article states they use User-Agent detection over feature detection. I hope they combine these solutions.
You can't use feature detection with a simple script tag. It's calling in a script and the cdn chooses the file to send based on the user-agent. No Javascript is run that would allow it to feature detect before choosing to send the load. There may be feature detection afterwards of course.
I think we're saying that most modern polyfills do a feature check before installing the polyfill... thus if you use Chrome with an IE agent, the polyfill still checks before implementing -- it's just a little slower than not installing the polyfill to begin with. Anyway, given the percentage of people who do this, UA detection seems like an acceptable tradeoff.