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@PeterPan_321Feb 02.2019 — #So @root#1600675 , Yes I know things get cached, but in my example (sans the error you pointed out, would the javascript result in pulling the image from cache? Even if the full URL is passed? Any way i could prove it?@PeterPan_321Feb 03.2019 — #Hmmm... and sadly the "worst case" (the browser where I MUST actually "load" images a second time, which is IE8) doesn't seem to have that in its network tools. What I'll have to do it add some "before"/"after" timers, and check the difference between loading an image already on the page, and an identically sized image that is NOT. @PeterPan_321Feb 08.2019 — #Whether an image already on the page, by virtue of <img src = "imagessomeImg.jpg"> will be cached, so that a subsequent javascript referring to the SAME (not unique) URL, such as...
will take much less time (if any) to complete the onload event, since the image is already in browser (cache) memory.
As as as i've been able to see, the second image load happens in something less than 1mS (about the best time resolution i can measure in JavaScript) , so I'm confident at this point that subsequent loads of the SAME image are being pulled from cache.@PeterPan_321Feb 10.2019 — #@root#1600866 I appreciate that, and know most of what you told me. I don't understand, however, why you tell me "So... what are you trying to prove", and then when I tell you what I was trying to prove, you respond with "Again, IDK what you are trying to prove or do".
I've written a few galleries too pre-loading images. This is a different case, and a different reason for the concern. But you've already said You don't care" what I'm trying to do, so I'll leave it there. Again, thanks for taking the time to answer. That in itself is very much appreciated.
Are subsequent image loads on same page faster?
Let’s say some image appears on an html page, and so is ‘loaded’ by the browser for display…
<div><img src=somefile.jpg” </img></div>
And then on the same page ,the same image src is ‘loaded’ again, maybe this time in a javascript chain of calls, triggered by the page body’s onload event.
.
[code=html]
<script>
function getImg() {
var img = new Image();
img.onload = function() {return img;}
img.src=’somefile.jpg’; // same file already on the page
}
</script>
<body onload=”getImg()” <body>
Will the second ‘load’ take as much time and memory as the first load of the page, or will it more likely be pulled from browser cache, and take minimal resources.
The background is, i need the original pixel width and height of certain images for subsequent layout and style calculations. Up till now I’ve been doing this server side with PHP, but I think a javascript solution might be better. And modern browsers *DO
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@PeterPan_321Feb 02.2019 — #So 0
@PeterPan_321Feb 03.2019 — #0
@PeterPan_321Feb 08.2019 — #Whether an image already on the page, by virtue of <img src = "imagessomeImg.jpg"> will be cached, so that a subsequent javascript referring to the SAME (not unique) URL, such as...[code=javascript ]
var img = new Image();
img.onload = function() { w = this.width; h= this.height; }
img.src = = "imagessomeImg.jpg"; // same image loaded in page
[/code]will take much less time (if any) to complete the onload event, since the image is already in browser (cache) memory.
As as as i've been able to see, the second image load happens in something less than 1mS (about the best time resolution i can measure in JavaScript) , so I'm confident at this point that subsequent loads of the SAME image are being pulled from cache.
0
@PeterPan_321Feb 10.2019 — #I've written a few galleries too pre-loading images. This is a different case, and a different reason for the concern. But you've already said You don't care" what I'm trying to do, so I'll leave it there. Again, thanks for taking the time to answer. That in itself is very much appreciated.