javascript - How to force browsers prefetch images in first 6 parallel connections -


i've found lot of techniques preload images both css , js, none of them able preload images way need, or more in order need.

simply put browser preload images , stuff in 1 block, the order in each image downloaded browser totally on own calculation, (and totally reasonably) top elements in document downloaded first.

unfortunately quite true in tests <img> elements only; other elements background images it's not that, if images used background <body> element example.

the solution far worked way needed place <img>elements right after <body>tag , set them style="display:none". this working, rather ugly , terribly rough way imo achieve this.

i'm bit concerned seo, since bots find right @ start of document hidden images purpose (i'm preloading images preloaders effects "loading.." small logo image).

i quite charmed super brilliant solution saw preload images pseudo element on body body:before , use multiple background images. while technique indeed works preload, won't effect loading order priority... sad it's perfect! :(

isn't there really other way force preload stuff top priority on rest of assets without cluttering top of document hidden images?

update

as explain in comments below, i'm not concerned in having images loaded in particular order, want them downloaded before part of assets , other item in "download" chart, images render instantly inside browser along normal css layout rendering when page accessed.

update 2

more info: term "preload" indeed misguiding, more close term i'm looking "prefetch" goes this:

most browsers download 6 requests in parallel @ time, holding rest of downloads. if "really" need in top 6, lucky, else in next 6, or maybe 1 after , on.

what i'm trying find proper way tell "hey download first please" , in particular "this image". pointed out @farkas in answers below rel="subresource" indeed start pointed here, works "[..]suggests it’s downloaded lower priority stylesheets/scripts , fonts @ equal or higher priority images", indeed loaded first many other things, still no proper way break in 6 gold top spots.

net chart download

as can see, browser downloaded first styles, 1 of images needed loaded asap, scripts, leaving out other 2 images needed downloaded top priority.

to noted tho i've placed scripts not in head, placed @ bottom before closing </body>, , (as stated on top of question) i've marked images right after opening <body> tag, dark-pattern.jpg has been downloaded first, other 2 postponed

... </head> <body> <img src="dark-pattern.jpg" style="display:none"> <img src="preloader.jpg" style="display:none"> <img src="xs-style.png" style="display:none">  .. rest of code  ...

i'd know proper way say, "please have spot pictures, download stiles, script can come later".

is possible achieve this?

i've found more detail on matter in here too, nothing on specific request apart rel="subresource"

ps. if thing has specific technical name, please let me know can give beast name, :p

try this:

var = ['img1.jpg','img2.jpg']; function onallimagesloaded() { alert('loaded!'); } function preload() {     var = new image();     var src= all.pop();     if (!src) {          onallimagesloaded();          return;     }     i.src = src;      i.onload = preload; } preload();

there issues cached images in ie, may omit onload call cached resources.

edit

you can use nice plugin designed track images loading (but doesn't preserve images order, images loaded simultaneously):

http://imagesloaded.desandro.com/


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