July 2018
Intermediate to advanced
354 pages
8h 51m
English
Content preview from Progressive Web Application Development by Example
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Lazy loading images
Images can delay your overall page load experience due to image numbers and their size. There are different strategies for optimizing image delivery. The first one you should consider is lazy loading images below the fold.
This could be a very tricky technique to execute. Modern APIs can help you, the IntersectionObserver (https://developer.mozilla.org/en-US/docs/Web/API/Intersection_Observer_API) API in particular gives you the ability to detect when elements are entering the viewport. You can designate the distance and time estimated threshold for an element to appear.
The IntersectionObserver API will trigger an event to let you know when an element is about to be displayed. At this point, you can initiate an image ...
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I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
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I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.