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JavaScript Preloader
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| <!doctype html> | |
| <html> | |
| <head> | |
| <meta charset="utf-8" /> | |
| <title>Preload</title> | |
| </head> | |
| <body> | |
| <progress id="loading" value="0"></progress> | |
| <script src="preload.js"></script> | |
| <script> | |
| var images = [ | |
| "http://placehold.it/100x100&text=1", | |
| "http://placehold.it/100x100&text=2", | |
| "http://placehold.it/100x100&text=3", | |
| "http://placehold.it/100x100&text=4", | |
| "http://placehold.it/100x100&text=5" | |
| ]; | |
| var loading = document.querySelector("#loading"); | |
| document.addEventListener("image_loaded", function (event) { | |
| loading.value = event.detail.loaded; | |
| loading.max = event.detail.total; | |
| }); | |
| var loader = new Preload(images) | |
| .then( | |
| function (images) { | |
| images.forEach(function (image) { | |
| document.body.appendChild(image); | |
| }); | |
| }, | |
| function () { | |
| var message = document.createElement('p'); | |
| message.style.color = "red"; | |
| message.innerText = "Erreur lors du chargement des images."; | |
| document.body.appendChild(message); | |
| } | |
| ); | |
| </script> | |
| </body> | |
| </html> |
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| var Preload = function (images) { | |
| if (!Array.isArray(images)) { | |
| images = [images]; | |
| } | |
| this.images = images; | |
| this.loaded = 0; | |
| var loaders = this.images.map(this.createLoader.bind(this)); | |
| return Promise.all(loaders); | |
| }; | |
| Preload.prototype.createLoader = function (src) { | |
| var loader = new Promise( | |
| function (resolve, reject) { | |
| var img = new Image(); | |
| img.onload = function () { | |
| resolve(img); | |
| }; | |
| img.onerror = function () { | |
| reject(Error("Image loading error.")); | |
| }; | |
| img.onabort = function () { | |
| reject(Error("Abort loading image.")); | |
| }; | |
| img.src = src; | |
| } | |
| ); | |
| loader.then( | |
| function () { | |
| this.loaded++; | |
| }.bind(this), | |
| function () {} | |
| ); | |
| loader.then( | |
| function () { | |
| document.dispatchEvent( | |
| new CustomEvent("image_loaded", { | |
| "detail": { | |
| "loaded": this.loaded, | |
| "total": this.images.length | |
| } | |
| }) | |
| ); | |
| }.bind(this), | |
| function () {} | |
| ); | |
| return loader; | |
| }; |
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