Why would I need image placeholder service or library?

Question

Yesterday, I saw a tweet saying about holderJS library. When I read the usage, it says it will generate the image placeholder completely on client side. So I am wondering why in the life would I need a placeholder library?

What is the scenario in which rather than placing div of some size I would use image placeholder?

Answer 1

Image placeholders are generally meant for a page that is either in the process of dynamically loading a real image or the page is only partially designed and the placeholder image shows how the design will be laid out and how big the image should be even though the real image is not yet available. In this way, the HTML design can be nearly completed even though the final images are not yet available or done.

Wikipedia uses image placeholders when they know they want a particular image in a page, but are in search of an image they can use with the appropriate license.

Image placeholders are traditionally served up by a service on the web that automatically creates the placeholder images based on query parameters in a URL, but the holder.js library creates placeholder images entirely on the client (so no outside services are needed).

You can certainly achieve the same look as a placeholder with just a div with a background color and perhaps even some text in the div. But, when someone wanted to plug the final images into place, they would have the change the div tags to img tags. When using a placeholder image, all the HTML tags can be final and left as they are, only the .src values need to be plugged in to finish the design. So, placeholder images allow you to have a closer to complete version of the HTML even though the images are not yet done. It's a minor different, but one that is appreciated by some designers.