That page just wasted a lot of your cellular data because your screen can't do anything with all of that extra resolution. Ideally, the browser should fetch a version of the image that's just a little wider than your screen size, say pixels. This ensures a high-resolution image without wasting data. And, even better, the image will load faster. Responsive images enable browsers to fetch different image resources to different devices.
If you don't use an image CDN you need to save multiple dimensions for each image and specify them in the srcset attribute. The w value tells the browser the width of each version. Depending on the device, the browser can choose the appropriate one:. Preload lets you tell the browser about critical resources that you want to load as soon as possible, before they are discovered in HTML. This is especially useful for resources that are not easily discoverable, such as fonts included in stylesheets, background images, or resources loaded from a script.
Responsive images and preload have been available for the last few years, but at the same time something was missing: there was no way to preload responsive images. Starting in Chrome 73 , the browser can preload the right variant of responsive images specified in srcset before it discovers the img tag! Depending on your site's structure, that could mean significantly faster image display!
We ran tests on a site that uses JavaScript to lazy-load responsive images. Preloading resulted in images loading 1. Responsive images are supported in all modern browsers while preloading them is supported only in Chromium-based browsers. This kicks off a request using the same resource selection logic that srcset and sizes will apply. Note: video preloading is included in the Preload spec, but is not currently implemented by browsers. Note: There's more detail about these values and the web features they expect to be consumed by in the Preload spec — see link element extensions.
Also note that the full list of values the as attribute can take is governed by the Fetch spec — see request destinations.
This is especially useful when preloading resources — the browser will use the type attribute value to work out if it supports that resource, and will only download it if so, ignoring it if not. You can see an example of this in our video example see the full source code , and also the live version , a code snippet from which is shown below. Therefore, specifying preloading for multiple types of the same resource is discouraged. Instead, the best practice is to specify preloading only for the type the majority of your users are likely to actually use.
When preloading resources that are fetched with CORS enabled e. The attribute needs to be set to match the resource's CORS and credentials mode, even when the fetch is not cross-origin.
As mentioned above, one interesting case where this applies is font files. Because of various reasons, these have to be fetched using anonymous-mode CORS see Font fetching requirements.
Let's use this case as an example. Active 17 days ago. Viewed k times. Improve this question. Mark Amery k 62 62 gold badges silver badges bronze badges. Francisc Francisc 69k 58 58 gold badges silver badges bronze badges. Note that some all?
To avoid this, keep a reference to the img object, e. What do you mean by "release the image"? If it was cached by the browser, it will stay there, right? A bit shorter: new Image. Even shorter: new Image. Show 11 more comments. Active Oldest Votes. This should work on all major browsers. Improve this answer. Alex M. Huzi Javiator Huzi Javiator 3, 1 1 gold badge 14 14 silver badges 5 5 bronze badges. Moderator Note: Please stop flagging this as "not an answer".
It is, in fact, a direct answer to the question that was asked. If you think the answer is wrong, or insufficiently supported with evidence, then downvote it. Add a comment. For anyone interested, here's some alternatives to code provided by OP. Sandwich 2, 2 2 gold badges 22 22 silver badges 28 28 bronze badges. Could you explain why this is better? BeNice I think you're misunderstanding, loading images is async, therefore you have to handle the onload state or you're just instantiating images in memory.
If you use this solution, don't forget the var statement for the i-variable. Otherwise it will be set globally which can cause error that are really hard to solve unless you know that you forgot the var statement. Mohammer thanks for this, I just copied the code from the link I provided. I will edit the code now to add the var — clintgh. Show 5 more comments. Alexander Alexander 6, 3 3 gold badges 45 45 silver badges 61 61 bronze badges. Thanks mplungjan.
Although it doesn't help me with this particular case, it is good to know. Am I right saying this will slow down loading of the page because these images need to be downloaded before the page can launch the load event? I do not believe these will work on all browsers. I know that on Chrome images are not loaded until they are visible. Will need to remove the display: none; and instead try and position them so they cannot be seen.
Can then hide with JS after everything has loaded if needed.
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