Le 16/05/2013 15:22, Yoav Weiss a écrit :
Arguably, the biggest problem in responsive Web design today is the fact
that many resource loading mechanisms are media query agnostic, and
download resources upfront regardless of whether they will be used or not.
One of the biggest resources in question (right after images) is external
JavaScript. JavaScript also has secondary performance effects, beside its
download size, since parsing and running it are also time (& battery)
consuming operations.
Currently authors that want their scripts to load only under certain
viewport sizes are forced to use JS based script loaders, which have the
side-effect of preventing these scripts from being parsed out by the
preloader.
How bad is the current situation with JS-based loaders? I would expect a
JS-based loader and the couple of feature-detection tests to be rather
small as well as heavily cachable, so not that awful for performance.
I'm not sure I understand your point about preloading scripts parsing.
Do you want them to be preparsed (which costs in battery as you mention)
or not preparsed (which will result in longer time when actually needing
the script)?
I believe that an HTML based solution would be a better fit, will be easier
to use by authors, and will enable preloaders to do their job and preload
these scripts.
How much time can be expected to be gained from such a feature given the
state-of-the-art JS loaders?
Overall, what is the expected gain between a JS-based loader and a
declarative media-aware loader? 1ms? 100ms?
Thanks,
David
