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asset-loader.js
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asset-loader.js
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const Assets = new (class Assets {
constructor () {
this.loading = new Set()
this.loaded = new Set()
this.listeners = {}
}
loadStyle (url) {
return this.load(url, (resolve) => {
const link = document.createElement('link')
link.rel = "stylesheet"
link.onload = resolve
link.href = url
document.head.appendChild(link)
})
}
loadScript (url) {
return this.load(url, (resolve) => {
const script = document.createElement('script')
script.type = "text/javascript";
script.src = url
script.onload = () => {
document.body.removeChild(script)
resolve()
}
document.body.appendChild(script)
})
}
load (url, processor) {
return new Promise((resolve) => {
if (this.loaded.has(url)) {
resolve()
} else if (this.loading.has(url)) {
this.listeners[url].push(resolve)
} else {
this.listeners[url] = [resolve]
this.loading.add(url)
processor(() => {
this.onLoad(url)
})
}
})
}
loadAll (method, urls) {
return new Promise((resolve, reject) => {
const items = urls.slice()
const next = async () => {
const url = items.shift()
if (url) {
await method(url)
await next()
} else {
resolve()
}
}
next()
})
}
onLoad(url) {
this.loading.delete(url)
for (let listener of this.listeners[url] || []) {
listener()
}
delete this.listeners[url]
this.loaded.add(url)
}
});