I have been searching for all available solutions
This is the best so far i could find but it doesn't work as it should be
It works for first few images then stops. Then i refresh page, works for few more images and then stops again.
So basically what i want to achieve is, give like a 100 images to a function, it starts downloading them 1 by 1
So browser caches those images and those images are not downloaded on other pages and instantly displayed
I want this images to be cached on mobile as well
Here my javascript code that i call. Actually i have more than 100 images but didn't put all here
I accept both jquery and raw javascript solutions doesn't matter
(function() {
'use strict';
var preLoader = function(images, options) {
this.options = {
pipeline: true,
auto: true,
/* onProgress: function(){}, */
/* onError: function(){}, */
onComplete: function() {}
};
options && typeof options == 'object' && this.setOptions(options);
this.addQueue(images);
this.queue.length && this.options.auto && this.processQueue();
};
preLoader.prototype.setOptions = function(options) {
// shallow copy
var o = this.options,
key;
for (key in options) options.hasOwnProperty(key) && (o[key] = options[key]);
return this;
};
preLoader.prototype.addQueue = function(images) {
// stores a local array, dereferenced from original
this.queue = images.slice();
return this;
};
preLoader.prototype.reset = function() {
// reset the arrays
this.completed = [];
this.errors = [];
return this;
};
preLoader.prototype.load = function(src, index) {
console.log("downloading image " + src);
var image = new Image(),
self = this,
o = this.options;
// set some event handlers
image.onerror = image.onabort = function() {
this.onerror = this.onabort = this.onload = null;
self.errors.push(src);
o.onError && o.onError.call(self, src);
checkProgress.call(self, src);
o.pipeline && self.loadNext(index);
};
image.onload = function() {
this.onerror = this.onabort = this.onload = null;
// store progress. this === image
self.completed.push(src); // this.src may differ
checkProgress.call(self, src, this);
o.pipeline && self.loadNext(index);
};
// actually load
image.src = src;
return this;
};
preLoader.prototype.loadNext = function(index) {
// when pipeline loading is enabled, calls next item
index++;
this.queue[index] && this.load(this.queue[index], index);
return this;
};
preLoader.prototype.processQueue = function() {
// runs through all queued items.
var i = 0,
queue = this.queue,
len = queue.length;
// process all queue items
this.reset();
if (!this.options.pipeline)
for (; i < len; ++i) this.load(queue[i], i);
else this.load(queue[0], 0);
return this;
};
function checkProgress(src, image) {
// intermediate checker for queue remaining. not exported.
// called on preLoader instance as scope
var args = [],
o = this.options;
// call onProgress
o.onProgress && src && o.onProgress.call(this, src, image, this.completed.length);
if (this.completed.length + this.errors.length === this.queue.length) {
args.push(this.completed);
this.errors.length && args.push(this.errors);
o.onComplete.apply(this, args);
}
return this;
}
if (typeof define === 'function' && define.amd) {
// we have an AMD loader.
define(function() {
return preLoader;
});
} else {
this.preLoader = preLoader;
}
}).call(this);
// Usage:
$(window).load(function() {
new preLoader([
'//static.pokemonpets.com/images/attack_animations/absorb1.png',
'//static.pokemonpets.com/images/attack_animations/bleeding1.png',
'//static.pokemonpets.com/images/attack_animations/bug_attack1.png',
'//static.pokemonpets.com/images/attack_animations/bug_attack2.png',
'//static.pokemonpets.com/images/attack_animations/bug_boost1.png',
'//static.pokemonpets.com/images/attack_animations/burned1.png',
'//static.pokemonpets.com/images/attack_animations/change_weather_cloud.png',
'//static.pokemonpets.com/images/attack_animations/confused1.png',
'//static.pokemonpets.com/images/attack_animations/copy_all_enemy_moves.png',
'//static.pokemonpets.com/images/attack_animations/copy_last_move_enemy.png',
'//static.pokemonpets.com/images/attack_animations/cringed1.png',
'//static.pokemonpets.com/images/attack_animations/critical1.png',
'//static.pokemonpets.com/images/attack_animations/cure_all_status_problems.png',
'//static.pokemonpets.com/images/attack_animations/dark_attack1.png',
'//static.pokemonpets.com/images/attack_animations/dark_attack2.png',
'//static.pokemonpets.com/images/attack_animations/dark_attack3.png',
'//static.pokemonpets.com/images/attack_animations/dark_boost1.png',
'//static.pokemonpets.com/images/attack_animations/double_effect.png',
'//static.pokemonpets.com/images/attack_animations/dragon_attack1.png',
'//static.pokemonpets.com/images/attack_animations/dragon_attack2.png',
'//static.pokemonpets.com/images/attack_animations/dragon_attack3.png',
'//static.pokemonpets.com/images/attack_animations/dragon_attack4.png'
]);
});
Something like this?
I do not have time to make it pretty.
const pref = "https://static.pokemonpets.com/images/attack_animations/";
const defa = "https://imgplaceholder.com/20x20/000/fff/fa-image";
const images=['absorb1','bleeding1','bug_attack1','bug_attack2','bug_boost1','burned1','change_weather_cloud','confused1','copy_all_enemy_moves','copy_last_move_enemy','cringed1','critical1','cure_all_status_problems','dark_attack1','dark_attack2','dark_attack3','dark_boost1','double_effect','dragon_attack1','dragon_attack2','dragon_attack3','dragon_attack4'];
let cnt = 0;
function loadIt() {
if (cnt >= images.length) return;
$("#imagecontainer > img").eq(cnt).attr("src",pref+images[cnt]+".png"); // preload next
cnt++;
}
const $cont = $("#container");
const $icont = $("#imagecontainer");
// setting up test images
$.each(images,function(_,im) {
$cont.append('<img src="'+defa+'" id="'+im+'"/>'); // actual images
$icont.append('<img src="'+defa+'" data-id="'+im+'"/>'); // preload images
});
$("#imagecontainer > img").on("load",function() {
if (this.src.indexOf("imgplaceholder") ==-1) { // not for the default image
$("#"+$(this).attr("data-id")).attr("src",this.src); // copy preloaded
loadIt(); // run for next entry
}
})
loadIt(); // run#imagecontainer img { height:20px }
#container img { height:100px }<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<div id="container"></div>
<hr/>
<div id="imagecontainer"></div>