A Deep Dive into Native Lazy-Loading for Images and Frames
CSS - Tricks
MAY 15, 2019
Most libraries work like this: The initial, server-side HTML response includes an img element without the src attribute so the browser does not load any data. Make sure your servers support the HTTP Range: 0-2047 header and respond with status code 206 (Partial Content) to prevent them from delivering the full image twice.
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