It is like knowing how this gentle appearance of images works.

I like to know how the smooth appearance of images is implemented? In addition, the direct display of high efficiency is still highly efficient in this way. it is like knowing how this gentle image effect works.
Http://down.chinaz.com/class/55_1.htm
The image shown on the above website is only loaded when it appears. The effect is smooth transition.

How to implement it?

In addition, the efficiency of direct display is still high.

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This is the effect of delayed loading of images, avoiding slow page loading due to excessive http connection requests during initial page loading.


Search for lazyload
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The imgtag is a gray image of grep.jpg, a negative image. since the URL is used to access the page at the beginning, it saves traffic when the image is downloaded and cached.

Others are triggered by scroll events. The author adds an original attribute to the tag to record the actual image URL. when the image is rolled to the field of view, the original is set to src, so I began to download the image.

The landlord can take the code directly and check whether it is written by jq. There are many js code on the Internet, which is not complicated. It just traverses the labels of a class every time to see if they are on the screen. just change src.

Http://down.chinaz.com/js/imgload.js this site's lazyload JS
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It looks amazing, but it seems that I don't know how to apply it. JS is downloaded, which is terrible! Alas... I hope you can describe it in detail upstairs.